#include <bits/stdc++.h>
using namespace std;
template <typename T>
inline T SUM(const vector<T>& v) {
  return accumulate(begin(v), end(v), T(0), [](T a, T b) { return a + b; });
}
bool isPrime(unsigned long long n) {
  if (n == 0 || n == 1) return false;
  if (n == 2 || n == 3 || n == 5 || n == 7) return true;
  if (n % 2 == 0 || n % 3 == 0) return false;
  for (int i = 5; i * i <= n; i += 6)
    if (n % i == 0 || n % (i + 2) == 0) return false;
  return true;
}
int main() {
  ios::sync_with_stdio(false);
  int N;
  cin >> N;
  vector<int> arr(N);
  int nb_ones = 0;
  int cand = -1;
  for (int i = 0; i < N; i++) {
    cin >> arr[i];
    if (arr[i] == 1) nb_ones++;
    if (isPrime(arr[i] + 1) && arr[i] != 1) cand = arr[i];
  }
  int tot = nb_ones;
  if (nb_ones > 0 && cand != -1) tot++;
  if (tot >= 2) {
    cout << tot << endl;
    arr = vector<int>(nb_ones, 1);
    if (cand != -1) arr.push_back(cand);
    {
      copy(begin(arr), end(arr) - 1, ostream_iterator<int>(cout, " "));
      cout << *(end(arr) - 1) << endl;
    };
    return 0;
  }
  for (int i = 0; i < N; i++) {
    for (int j = i + 1; j < N; j++) {
      if (isPrime(arr[i] + arr[j])) {
        cout << 2 << endl << arr[i] << " " << arr[j] << endl;
        return 0;
      }
    }
  }
  cout << 1 << endl << arr[0] << endl;
  return 0;
}
