#include <bits/stdc++.h>
#pragma GCC optimize("Ofast,no-stack-protector,unroll-loops,fast-math,O3")
#pragma GCC optimize("trapv")
#pragma GCC target( \
    "sse,sse2,sse3,ssse3,sse4,sse4.2,popcnt,abm,mmx,avx2,tune=native")
#pragma GCC optimize("-ffast-math")
#pragma GCC optimize("-funroll-loops")
#pragma GCC optimize("-funroll-all-loops,-fpeel-loops,-funswitch-loops")
using namespace std;
using graph = vector<vector<int>>;
using wgraph = vector<vector<pair<int, int>>>;
using idwgraph = vector<vector<pair<int, pair<int, int>>>>;
using ll = long long;
template <class A, class B>
ostream& operator<<(ostream& o, pair<A, B>& p) {
  return o << "(" << p.first << ", " << p.second << ")";
}
template <class RandomIt>
ostream& printIterable(ostream& o, RandomIt first, RandomIt second) {
  for (; first < second; ++first) o << (*first) << " ";
  return o;
}
template <class A>
istream& operator>>(istream& is, vector<A>& a) {
  for (auto& v : a) is >> v;
  return is;
}
template <class A>
ostream& operator<<(ostream& o, vector<A>& a) {
  return printIterable(o, a.begin(), a.end());
}
template <class A>
ostream& operator<<(ostream& o, set<A>& a) {
  return printIterable(o, a.begin(), a.end());
}
template <class A>
ostream& operator<<(ostream& o, multiset<A>& a) {
  return printIterable(o, a.begin(), a.end());
}
template <class T>
T fmax(T a, T b) {
  return a > b ? a : b;
}
template <class T>
T fmin(T a, T b) {
  return a < b ? a : b;
}
template <class T>
struct is_iterator {
  template <class U, typename enable_if<!is_convertible<U, const char*>::value,
                                        int>::type = 0>
  constexpr static auto has_indirection(int)
      -> decltype(*declval<U>(), bool()) {
    return true;
  }
  template <class>
  constexpr static bool has_indirection(long) {
    return false;
  }
  constexpr static bool value = has_indirection<T>(0);
};
using uint = unsigned int;
const uint BUFFER_SIZE = 1 << 12;
const uint MAX_LENGTH = 1 << 7;
namespace Detail {
struct Width {
  uint value;
};
struct Fill {
  char value;
};
struct Base {
  uint value;
};
struct Precision {
  uint value;
};
struct Delimiter {
  const char* value;
};
}  // namespace Detail
Detail::Width setWidth(uint value = 0) { return {value}; }
Detail::Fill setFill(char value = ' ') { return {value}; }
Detail::Base setBase(uint value = 10) {
  assert(2 <= value && value <= 36);
  return {value};
}
Detail::Precision setPrecision(uint value = 9) {
  assert(value < MAX_LENGTH);
  return {value};
}
Detail::Delimiter setDelimiter(const char* value = " ") { return {value}; }
class InputDevice {
 protected:
  const char* head;
  const char* tail;
  InputDevice(const char* head, const char* tail)
      : head(head), tail(tail), base(setBase().value) {}
  virtual void fillInput() = 0;
  inline char nextChar() {
    if (__builtin_expect(head >= tail, false)) fillInput();
    return *head++;
  }
  template <class I>
  int readUnsignedIntGeneral(I& arg, char c) {
    I value = 0;
    int length = 0;
    for (;; ++length, c = nextChar()) {
      if (isDigit(c))
        c -= '0';
      else if (isUpper(c))
        c -= 'A' - 10;
      else if (isLower(c))
        c -= 'a' - 10;
      else
        c = base;
      if (c >= base) break;
      value = base * value + c;
    }
    arg = value;
    return --head, length;
  }
  template <class I>
  inline int readUnsignedInt(I& arg, char c) {
    if (__builtin_expect(base > 10, false))
      return readUnsignedIntGeneral(arg, c);
    I value = 0;
    int length = 0;
    for (; static_cast<unsigned char>(c - '0') < base; ++length, c = nextChar())
      value = base * value + c - '0';
    arg = value;
    return --head, length;
  }
  template <class I>
  inline bool readSignedInt(I& arg, char c) {
    bool negative = c == '-';
    if (negative) c = nextChar();
    typename make_unsigned<I>::type unsignedArg;
    if (readUnsignedInt(unsignedArg, c) == 0) return false;
    arg = negative ? ~static_cast<I>(unsignedArg - 1)
                   : static_cast<I>(unsignedArg);
    return true;
  }
  template <class F>
  bool readFloatingPoint(F& arg, char c) {
    bool negative = c == '-';
    if (negative) c = nextChar();
    unsigned long long integerPart;
    if (readUnsignedInt(integerPart, c) == 0) return false;
    arg = static_cast<F>(integerPart);
    if (nextChar() == '.') {
      unsigned long long fractionalPart = 0;
      int fractionalLength = readUnsignedInt(fractionalPart, nextChar());
      if (fractionalLength > 0) {
        unsigned long long basePower = 1;
        for (; fractionalLength; --fractionalLength) basePower *= base;
        arg += static_cast<F>(fractionalPart) / basePower;
      }
    } else
      --head;
    if (negative) arg = -arg;
    return true;
  }

 public:
  uint base;
  InputDevice(InputDevice const&) = delete;
  InputDevice& operator=(InputDevice const&) = delete;
  static inline bool isSpace(char c) {
    return static_cast<unsigned char>(c - '\t') < 5 || c == ' ';
  }
  static inline bool isDigit(char c) {
    return static_cast<unsigned char>(c - '0') < 10;
  }
  static inline bool isUpper(char c) {
    return static_cast<unsigned char>(c - 'A') < 26;
  }
  static inline bool isLower(char c) {
    return static_cast<unsigned char>(c - 'a') < 26;
  }
  static inline bool isOneOf(char c, const char* str) {
    return strchr(str, c) != nullptr;
  }
  void putBack() { --head; }
  inline bool readChar(char& arg) {
    if (__builtin_expect(head >= tail, false)) {
      fillInput();
      if (__builtin_expect(head >= tail, false)) return arg = '\0', false;
    }
    return arg = *head++, true;
  }
  template <class UnaryPredicate>
  inline char skipCharacters(UnaryPredicate isSkipped) {
    char c;
    do {
      c = nextChar();
    } while (isSkipped(c));
    return c;
  }
  inline char skipCharacters() { return skipCharacters(isSpace); }
  template <class UnaryPredicate>
  inline int readString(char* arg, int limit, UnaryPredicate isTerminator) {
    skipCharacters(isTerminator);
    int charsRead = 0;
    for (--head, --limit; head < tail; fillInput()) {
      ptrdiff_t chunkSize =
          find_if(head, min(tail, head + limit - charsRead), isTerminator) -
          head;
      arg = copy_n(head, chunkSize, arg);
      head += chunkSize;
      charsRead += chunkSize;
      if (chunkSize == 0 || head < tail) break;
    }
    return *arg = '\0', charsRead;
  }
  inline int readString(char* arg, int limit, const char* terminators) {
    if (!*terminators) return readString(arg, limit, InputDevice::isSpace);
    return readString(arg, limit, [terminators](char c) {
      return InputDevice::isOneOf(c, terminators);
    });
  }
  inline bool read(Detail::Base newBase) {
    base = newBase.value;
    return true;
  }
  inline bool read() { return true; }
  inline bool read(char& arg) { return readChar(arg); }
  template <class I>
  inline typename enable_if<is_integral<I>::value && is_unsigned<I>::value,
                            bool>::type
  read(I& arg) {
    return readUnsignedInt(arg, skipCharacters()) > 0;
  }
  template <class I>
  inline typename enable_if<is_integral<I>::value && is_signed<I>::value,
                            bool>::type
  read(I& arg) {
    return readSignedInt(arg, skipCharacters());
  }
  template <class F>
  inline typename enable_if<is_floating_point<F>::value, bool>::type read(
      F& arg) {
    return readFloatingPoint(arg, skipCharacters());
  }
  inline bool read(const char& arg) {
    skipCharacters([arg](char c) { return arg != c; });
    return true;
  }
  inline bool read(const char* arg) {
    if (*arg)
      skipCharacters([arg](char c) { return InputDevice::isOneOf(c, arg); });
    else
      skipCharacters();
    return putBack(), true;
  }
  inline bool read(bool (*isSkipped)(char)) {
    skipCharacters(isSkipped);
    putBack();
    return true;
  }
  template <class I, class Terminator, class... Ts>
  inline typename enable_if<is_integral<I>::value, bool>::type read(
      char* arg, I limit, Terminator terminator, Ts&&... args) {
    readString(arg, static_cast<int>(limit), terminator);
    return read(forward<Ts>(args)...);
  }
  template <class I>
  inline typename enable_if<is_integral<I>::value, bool>::type read(char* arg,
                                                                    I limit) {
    return read(arg, limit, "");
  }
  template <class... Ts>
  inline bool read(char* first, char* last, Ts&&... args) {
    return read(first, static_cast<int>(last - first), forward<Ts>(args)...);
  }
  template <int N, class... Ts>
  inline bool read(char (&arg)[N], Ts&&... args) {
    return read(static_cast<char*>(arg), N, forward<Ts>(args)...);
  }
  template <class Terminator, class... Ts>
  inline bool read(string& arg, Terminator terminator, Ts&&... args) {
    for (int length = 16, last = 0;; last += length, length <<= 1) {
      arg.resize(last + length);
      int charsRead = readString(&arg[last], length + 1, terminator);
      if (charsRead < length) {
        arg.resize(last + charsRead);
        return read(forward<Ts>(args)...);
      }
    }
  }
  inline bool read(string& arg) { return read(arg, ""); }
  template <class T1, class T2>
  inline bool read(pair<T1, T2>& arg) {
    return read(arg.first, arg.second);
  }
  template <class T>
  inline bool read(complex<T>& arg) {
    T real, imag;
    if (!read(real, imag)) return false;
    arg.real(real), arg.imag(imag);
    return true;
  }
  template <class T>
  inline bool read(vector<T>& arg) {
    uint n;
    if (!read(n)) return false;
    arg.resize(n);
    return read(arg.begin(), arg.end());
  }
  template <class Iterator, class... Ts>
  inline typename enable_if<is_iterator<Iterator>::value, bool>::type read(
      Iterator first, Iterator last, Ts&&... args) {
    for (; first != last; ++first)
      if (!read(*first)) return false;
    return read(forward<Ts>(args)...);
  }
  template <class Iterator, class I, class... Ts>
  inline
      typename enable_if<is_iterator<Iterator>::value && is_integral<I>::value,
                         bool>::type
      read(Iterator first, I count, Ts&&... args) {
    return read(first, first + count, forward<Ts>(args)...);
  }
  template <class T>
  inline auto read(T& arg) -> decltype(arg.read(*this)) {
    return arg.read(*this);
  }
  template <class T0, class T1, class... Ts>
  inline typename enable_if<
      !is_iterator<T0>::value && !is_convertible<T0, char*>::value, bool>::type
  read(T0&& arg0, T1&& arg1, Ts&&... args) {
    return read(forward<T0>(arg0)) &&
           read(forward<T1>(arg1), forward<Ts>(args)...);
  }
};
class InputFile : public InputDevice {
  FILE* file;
  bool lineBuffered;
  bool owner;
  char buffer[BUFFER_SIZE];
  void fillInput() override {
    head = buffer;
    *buffer = '\0';
    if (__builtin_expect(!lineBuffered, true)) {
      tail = head + fread(buffer, 1, BUFFER_SIZE, file);
    } else {
      tail = head;
      if (fgets(buffer, BUFFER_SIZE, file))
        while (*tail) ++tail;
    }
  }

 public:
  InputFile(FILE* file = stdin, bool lineBuffered = true,
            bool takeOwnership = false)
      : InputDevice(buffer, buffer),
        file(file),
        lineBuffered(lineBuffered),
        owner(takeOwnership) {}
  InputFile(const char* fileName)
      : InputFile(fopen(fileName, "r"), false, true) {}
  ~InputFile() {
    if (owner) fclose(file);
  }
};
class InputString : public InputDevice {
  void fillInput() override {
    while (*tail) ++tail;
  }

 public:
  InputString(const string& s) : InputDevice(s.data(), s.data() + s.size()) {}
  InputString(const char* s) : InputDevice(s, s + strlen(s)) {}
};
class OutputDevice {
 protected:
  char buffer[BUFFER_SIZE + MAX_LENGTH];
  char* output;
  char* end;
  bool separate;
  OutputDevice()
      : output(buffer),
        end(buffer + BUFFER_SIZE + MAX_LENGTH),
        separate(false),
        width(setWidth().value),
        fill(setFill().value),
        base(setBase().value),
        precision(setPrecision().value),
        delimiter(setDelimiter().value) {
    computeBasePower();
  }
  virtual void writeToDevice(uint count) = 0;
  inline void flushMaybe() {
    if (__builtin_expect(output >= buffer + BUFFER_SIZE, false)) {
      writeToDevice(BUFFER_SIZE);
      output = copy(buffer + BUFFER_SIZE, output, buffer);
    }
  }
  void computeBasePower() {
    basePower = 1;
    for (uint i = 0; i < precision; ++i) basePower *= base;
  }
  template <class I>
  inline char* writeUnsignedInt(I arg, char* last) {
    if (__builtin_expect(arg == 0, false)) *--last = '0';
    if (__builtin_expect(base == 10, true)) {
      for (; arg; arg /= 10) *--last = '0' + arg % 10;
    } else
      for (; arg; arg /= base) {
        I digit = arg % base;
        *--last = digit < 10 ? '0' + digit : 'A' - 10 + digit;
      }
    return last;
  }
  template <class I>
  inline char* writeSignedInt(I arg, char* last) {
    auto unsignedArg = static_cast<typename make_unsigned<I>::type>(arg);
    if (arg < 0) {
      last = writeUnsignedInt(~unsignedArg + 1, last);
      *--last = '-';
      return last;
    }
    return writeUnsignedInt(unsignedArg, last);
  }
  template <class F>
  char* writeFloatingPoint(F arg, char* last) {
    bool negative = signbit(arg);
    if (negative) arg = -arg;
    if (isnan(arg))
      for (int i = 0; i < 3; ++i) *--last = i["NaN"];
    else if (isinf(arg))
      for (int i = 0; i < 3; ++i) *--last = i["fnI"];
    else {
      auto integerPart = static_cast<unsigned long long>(arg);
      auto fractionalPart = static_cast<unsigned long long>(
          (arg - integerPart) * basePower + F(0.5));
      if (fractionalPart >= basePower) ++integerPart, fractionalPart = 0;
      char* point = last - precision;
      if (precision > 0) {
        ::fill(point, writeUnsignedInt(fractionalPart, last), '0');
        *--point = '.';
      }
      last = writeUnsignedInt(integerPart, point);
    }
    if (negative) *--last = '-';
    return last;
  }
  inline int writeT(char* first) {
    int delimiterLenght = separate ? writeDelimiter() : 0;
    separate = true;
    uint charsWritten = static_cast<uint>(end - first);
    if (__builtin_expect(charsWritten < width, false))
      charsWritten += writeFill(width - charsWritten);
    output = copy(first, end, output);
    flushMaybe();
    return delimiterLenght + static_cast<int>(charsWritten);
  }
  inline int writeFill(uint count) {
    int charsWritten = static_cast<int>(count);
    if (__builtin_expect(output + count + MAX_LENGTH < end, true)) {
      if (count == 1)
        *output++ = fill;
      else
        output = fill_n(output, count, fill);
    } else
      for (uint chunkSize = static_cast<uint>(buffer + BUFFER_SIZE - output);;
           chunkSize = BUFFER_SIZE) {
        if (chunkSize > count) chunkSize = count;
        output = fill_n(output, chunkSize, fill);
        flushMaybe();
        if ((count -= chunkSize) == 0) break;
      }
    return charsWritten;
  }

 public:
  uint width;
  char fill;
  uint base;
  uint precision;
  unsigned long long basePower;
  string delimiter;
  OutputDevice(OutputDevice const&) = delete;
  OutputDevice& operator=(OutputDevice const&) = delete;
  virtual ~OutputDevice(){};
  inline int writeChar(char arg) {
    separate = false;
    *output++ = arg;
    flushMaybe();
    return 1;
  }
  inline int writeString(const char* arg, size_t length,
                         bool checkWidth = true) {
    separate = false;
    uint count = static_cast<uint>(length);
    int charsWritten =
        static_cast<int>(count) +
        (checkWidth && count < width ? writeFill(width - count) : 0);
    if (__builtin_expect(output + count + MAX_LENGTH < end, true)) {
      if (count == 1)
        *output++ = *arg;
      else
        output = copy_n(arg, count, output);
    } else
      for (uint chunkSize = static_cast<uint>(buffer + BUFFER_SIZE - output);;
           chunkSize = BUFFER_SIZE) {
        if (chunkSize > count) chunkSize = count;
        output = copy_n(arg, chunkSize, output);
        flushMaybe();
        if ((count -= chunkSize) == 0) break;
        arg += chunkSize;
      }
    return charsWritten;
  }
  inline int writeDelimiter() {
    return writeString(delimiter.c_str(), delimiter.size(), false);
  }
  inline void flush() {
    writeToDevice(static_cast<uint>(output - buffer));
    output = buffer;
  }
  inline int write(Detail::Width newWidth) {
    width = newWidth.value;
    return 0;
  }
  inline int write(Detail::Fill newFill) {
    fill = newFill.value;
    return 0;
  }
  inline int write(Detail::Base newBase) {
    base = newBase.value;
    computeBasePower();
    return 0;
  }
  inline int write(Detail::Precision newPrecision) {
    precision = newPrecision.value;
    computeBasePower();
    return 0;
  }
  inline int write(Detail::Delimiter newDelimiter) {
    delimiter = newDelimiter.value;
    return 0;
  }
  inline int write() { return 0; }
  inline int write(char arg) { return writeChar(arg); }
  template <class I>
  inline typename enable_if<is_integral<I>::value && is_unsigned<I>::value,
                            int>::type
  write(I arg) {
    return writeT(writeUnsignedInt(arg, end));
  }
  template <class I>
  inline typename enable_if<is_integral<I>::value && is_signed<I>::value,
                            int>::type
  write(I arg) {
    return writeT(writeSignedInt(arg, end));
  }
  template <class F>
  inline typename enable_if<is_floating_point<F>::value, int>::type write(
      F arg) {
    return writeT(writeFloatingPoint(arg, end));
  }
  inline int write(const char* arg) { return writeString(arg, strlen(arg)); }
  template <int N>
  inline int write(char (&arg)[N]) {
    return writeString(arg, strlen(arg));
  }
  inline int write(const string& arg) {
    return writeString(arg.c_str(), arg.size());
  }
  template <class T1, class T2>
  inline int write(const pair<T1, T2>& arg) {
    int charsWritten = write(arg.first);
    charsWritten += writeDelimiter();
    return charsWritten + write(arg.second);
  }
  template <class T>
  inline int write(const complex<T>& arg) {
    return write(real(arg), imag(arg));
  }
  template <class Iterator, class... Ts>
  inline typename enable_if<is_iterator<Iterator>::value, int>::type write(
      Iterator first, Iterator last, Ts&&... args) {
    int charsWritten = 0;
    for (; first != last;
         charsWritten += ++first == last ? 0 : writeDelimiter())
      charsWritten += write(*first);
    return charsWritten + write(forward<Ts>(args)...);
  }
  template <class Iterator, class I, class... Ts>
  inline
      typename enable_if<is_iterator<Iterator>::value && is_integral<I>::value,
                         int>::type
      write(Iterator first, I count, Ts&&... args) {
    return write(first, first + count, forward<Ts>(args)...);
  }
  template <class T>
  inline auto write(const T& arg) -> decltype(arg.write(*this)) {
    return arg.write(*this);
  }
  template <class T0, class T1, class... Ts>
  inline typename enable_if<!is_iterator<T0>::value, int>::type write(
      T0&& arg0, T1&& arg1, Ts&&... args) {
    int charsWritten = write(forward<T0>(arg0));
    return charsWritten + write(forward<T1>(arg1), forward<Ts>(args)...);
  }
};
class OutputFile : public OutputDevice {
  FILE* file;
  bool owner;
  void writeToDevice(uint count) override {
    fwrite(buffer, 1, count, file);
    fflush(file);
  }

 public:
  OutputFile(FILE* file = stdout, bool takeOwnership = false)
      : file(file), owner(takeOwnership) {}
  OutputFile(const char* fileName) : OutputFile(fopen(fileName, "w"), true) {}
  ~OutputFile() override {
    flush();
    if (owner) fclose(file);
  }
};
class OutputString : public OutputDevice {
  string& str;
  void writeToDevice(uint count) override { str.append(buffer, count); }

 public:
  OutputString(string& str) : OutputDevice(), str(str) {}
  ~OutputString() override { flush(); }
};
unique_ptr<InputDevice> input;
unique_ptr<OutputDevice> output;
template <class... Ts>
inline bool read(Ts&&... args) {
  return input->read(forward<Ts>(args)...);
}
template <class... Ts>
inline int write(Ts&&... args) {
  return output->write(forward<Ts>(args)...);
}
template <class... Ts>
inline int writeln(Ts&&... args) {
  return write(forward<Ts>(args)..., '\n');
}
void flush() { output->flush(); }
bool sieve[100000];
void init() {
  memset(sieve, 1, sizeof sieve);
  sieve[0] = sieve[1] = false;
  for (int i = 2; i < 3000; i++)
    if (sieve[i])
      for (int j = i * i; j < 100000; j += i) sieve[j] = false;
}
void test_case() {
  int k;
  cin >> k;
  string s;
  cin >> s;
  vector<int> c(10);
  for (int i = 0; i < 10; i++) c[i] = count(s.begin(), s.end(), char('0' + i));
  if (c[2] + c[3] + c[5] + c[7] == k) {
    if (c[2] > 1) {
      cout << "2\n22\n";
      return;
    }
    if (c[3] > 1) {
      cout << "2\n33\n";
      return;
    }
    if (c[5] > 1) {
      cout << "2\n55\n";
      return;
    }
    if (c[7] > 1) {
      cout << "2\n77\n";
      return;
    }
    int ans = 178478748;
    for (int mask = 0; mask < (1 << k); mask++) {
      int num = 0;
      for (int i = 0; i < k; i++)
        if (mask & (1 << i)) num *= 10, num += s[i] - '0';
      if (!sieve[num] && num > 0) ans = min(ans, num);
    }
    cout << ((int)to_string(ans).size()) << "\n";
    cout << ans << "\n";
  } else {
    for (int i = 0; i < 10; i++) {
      if (c[i] > 0 && i != 2 && i != 3 && i != 5 && i != 7) {
        cout << 1 << "\n" << i << "\n";
        return;
      }
    }
  }
}
int main() {
  bool MULTITEST = true, AICashIO = false;
  init();
  if (AICashIO) {
    input.reset(new InputFile(stdin, false));
    output.reset(new OutputFile());
  } else {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
  }
  int tt = 1;
  if (MULTITEST) {
    if (AICashIO)
      read(tt);
    else
      cin >> tt;
  }
  while (tt--) test_case();
}
