#include <bits/stdc++.h>
using namespace std;
const int MOD = (int)1e9 + 7;
const int FFTMOD = 119 << 23 | 1;
const int INF = (int)1e9 + 23111992;
const long long LINF = (long long)1e18 + 23111992;
const long double PI = acos((long double)-1);
const long double EPS = 1e-9;
inline long long gcd(long long a, long long b) {
  long long r;
  while (b) {
    r = a % b;
    a = b;
    b = r;
  }
  return a;
}
inline long long lcm(long long a, long long b) { return a / gcd(a, b) * b; }
inline long long fpow(long long n, long long k, int p = MOD) {
  long long r = 1;
  for (; k; k >>= 1) {
    if (k & 1) r = r * n % p;
    n = n * n % p;
  }
  return r;
}
template <class T>
inline int chkmin(T& a, const T& val) {
  return val < a ? a = val, 1 : 0;
}
template <class T>
inline int chkmax(T& a, const T& val) {
  return a < val ? a = val, 1 : 0;
}
inline unsigned long long isqrt(unsigned long long k) {
  unsigned long long r = sqrt(k) + 1;
  while (r * r > k) r--;
  return r;
}
inline long long icbrt(long long k) {
  long long r = cbrt(k) + 1;
  while (r * r * r > k) r--;
  return r;
}
inline void addmod(int& a, int val, int p = MOD) {
  if ((a = (a + val)) >= p) a -= p;
}
inline void submod(int& a, int val, int p = MOD) {
  if ((a = (a - val)) < 0) a += p;
}
inline int mult(int a, int b, int p = MOD) { return (long long)a * b % p; }
inline int inv(int a, int p = MOD) { return fpow(a, p - 2, p); }
inline int sign(long double x) { return x < -EPS ? -1 : x > +EPS; }
inline int sign(long double x, long double y) { return sign(x - y); }
mt19937 mt(chrono::high_resolution_clock::now().time_since_epoch().count());
inline int myrand() { return abs((int)mt()); }
namespace FFT {
const int maxf = 1 << 18;
struct cp {
  long double x, y;
  cp(long double x = 0, long double y = 0) : x(x), y(y) {}
  cp operator+(const cp& rhs) const { return cp(x + rhs.x, y + rhs.y); }
  cp operator-(const cp& rhs) const { return cp(x - rhs.x, y - rhs.y); }
  cp operator*(const cp& rhs) const {
    return cp(x * rhs.x - y * rhs.y, x * rhs.y + y * rhs.x);
  }
  cp operator!() const { return cp(x, -y); }
} rts[maxf + 1];
cp fa[maxf], fb[maxf];
cp fc[maxf], fd[maxf];
int bitrev[maxf];
void fftinit() {
  int k = 0;
  while ((1 << k) < maxf) k++;
  bitrev[0] = 0;
  for (int i = 1; i < maxf; i++) {
    bitrev[i] = bitrev[i >> 1] >> 1 | ((i & 1) << k - 1);
  }
  long double PI = acos((long double)-1.0);
  rts[0] = rts[maxf] = cp(1, 0);
  for (int i = 1; i + i <= maxf; i++) {
    rts[i] = cp(cos(i * 2 * PI / maxf), sin(i * 2 * PI / maxf));
  }
  for (int i = maxf / 2 + 1; i < maxf; i++) {
    rts[i] = !rts[maxf - i];
  }
}
void dft(cp a[], int n, int sign) {
  static int isinit;
  if (!isinit) {
    isinit = 1;
    fftinit();
  }
  int d = 0;
  while ((1 << d) * n != maxf) d++;
  for (int i = 0; i < n; i++) {
    if (i < (bitrev[i] >> d)) {
      swap(a[i], a[bitrev[i] >> d]);
    }
  }
  for (int len = 2; len <= n; len <<= 1) {
    int delta = maxf / len * sign;
    for (int i = 0; i < n; i += len) {
      cp *x = a + i, *y = a + i + (len >> 1), *w = sign > 0 ? rts : rts + maxf;
      for (int k = 0; k + k < len; k++) {
        cp z = *y * *w;
        *y = *x - z, *x = *x + z;
        x++, y++, w += delta;
      }
    }
  }
  if (sign < 0) {
    for (int i = 0; i < n; i++) {
      a[i].x /= n;
      a[i].y /= n;
    }
  }
}
void multiply(int a[], int b[], int na, int nb, long long c[]) {
  int n = na + nb - 1;
  while (n != (n & -n)) n += n & -n;
  for (int i = 0; i < n; i++) fa[i] = fb[i] = cp();
  for (int i = 0; i < na; i++) fa[i] = cp(a[i]);
  for (int i = 0; i < nb; i++) fb[i] = cp(b[i]);
  dft(fa, n, 1), dft(fb, n, 1);
  for (int i = 0; i < n; i++) fa[i] = fa[i] * fb[i];
  dft(fa, n, -1);
  for (int i = 0; i < n; i++) c[i] = (long long)floor(fa[i].x + 0.5);
}
void multiply(int a[], int b[], int na, int nb, int c[], int& nc, int base,
              int dup) {
  int n = na + nb - 1;
  while (n != (n & -n)) n += n & -n;
  for (int i = 0; i < n; i++) fa[i] = fb[i] = cp();
  static const int magic = 15;
  for (int i = 0; i < na; i++)
    fa[i] = cp(a[i] >> magic, a[i] & (1 << magic) - 1);
  for (int i = 0; i < nb; i++)
    fb[i] = cp(b[i] >> magic, b[i] & (1 << magic) - 1);
  dft(fa, n, 1);
  if (dup) {
    for (int i = 0; i < n; i++) fb[i] = fa[i];
  } else {
    dft(fb, n, 1);
  }
  for (int i = 0; i < n; i++) {
    int j = (n - i) % n;
    cp x = fa[i] + !fa[j];
    cp y = fb[i] + !fb[j];
    cp z = !fa[j] - fa[i];
    cp t = !fb[j] - fb[i];
    fc[i] = (x * t + y * z) * cp(0, 0.25);
    fd[i] = x * y * cp(0, 0.25) + z * t * cp(-0.25, 0);
  }
  dft(fc, n, -1), dft(fd, n, -1);
  nc = 0;
  long long carry = 0;
  for (int i = 0; i < n; i++) {
    long long u = (long long)round(fc[i].x);
    long long v = (long long)round(fd[i].x);
    long long w = (long long)round(fd[i].y);
    long long ncarry = (u / base << 15) + (u % base << 15) / base + v / base +
                       (w / base << 30) + (w % base << 30) / base;
    assert(0 <= ncarry && ncarry < 2e18);
    long long t =
        (u % base << 15) % base + v % base + (w % base << 30) % base + carry;
    carry = ncarry + t / base;
    assert(carry < 2e18);
    c[nc++] = t % base;
  }
  while (carry) {
    c[nc++] = carry % base;
    carry /= base;
  }
}
vector<int> multiply(vector<int> a, vector<int> b, int base) {
  static int fa[maxf], fb[maxf], fc[maxf + 5];
  int na = a.size(), nb = b.size();
  for (int i = 0; i < na; i++) fa[i] = a[i];
  for (int i = 0; i < nb; i++) fb[i] = b[i];
  int nc = 0;
  multiply(fa, fb, na, nb, fc, nc, base, a == b);
  vector<int> res(nc);
  for (int i = 0; i < nc; i++) res[i] = fc[i];
  while (1 < res.size() && !res.back()) res.pop_back();
  return res;
}
}  // namespace FFT
const int base = 10;
const int nblock = 9;
const int blockbase = (int)round(pow(base, nblock));
struct Bigint {
  vector<int> a;
  int sign;
  Bigint() : sign(1) {}
  Bigint(long long v) { *this = v; }
  Bigint(const string& s) { read(s); }
  void operator=(const Bigint& v) {
    sign = v.sign;
    a = v.a;
  }
  void operator=(long long v) {
    a.clear();
    sign = 1;
    if (v < 0) sign = -1, v = -v;
    for (; v > 0; v = v / blockbase) a.push_back(v % blockbase);
  }
  Bigint operator+(const Bigint& v) const {
    if (sign == v.sign) {
      Bigint res = v;
      for (int i = 0, carry = 0; i < (int)max(a.size(), v.a.size()) || carry;
           i++) {
        if (i == (int)res.a.size()) res.a.push_back(0);
        res.a[i] += carry + (i < (int)a.size() ? a[i] : 0);
        carry = res.a[i] >= blockbase;
        if (carry) res.a[i] -= blockbase;
      }
      return res;
    }
    return *this - (-v);
  }
  Bigint operator-(const Bigint& v) const {
    if (sign == v.sign) {
      if (abs() >= v.abs()) {
        Bigint res = *this;
        for (int i = 0, carry = 0; i < (int)v.a.size() || carry; i++) {
          res.a[i] -= carry + (i < (int)v.a.size() ? v.a[i] : 0);
          carry = res.a[i] < 0;
          if (carry) res.a[i] += blockbase;
        }
        res.trim();
        return res;
      }
      return -(v - *this);
    }
    return *this + (-v);
  }
  void operator*=(int v) {
    if (v < 0) sign = -sign, v = -v;
    for (int i = 0, carry = 0; i < (int)a.size() || carry; i++) {
      if (i == (int)a.size()) a.push_back(0);
      long long cur = a[i] * (long long)v + carry;
      carry = (int)(cur / blockbase);
      a[i] = (int)(cur % blockbase);
    }
    trim();
  }
  void operator*=(long long v) {
    if (v >= (long long)blockbase * blockbase) {
      *this *= Bigint(v);
    }
    int a = v / blockbase;
    int b = v % blockbase;
    *this = *this * a * blockbase + *this * b;
  }
  Bigint operator*(int v) const {
    Bigint res = *this;
    res *= v;
    return res;
  }
  Bigint operator*(long long v) const {
    Bigint res = *this;
    res *= v;
    return res;
  }
  friend pair<Bigint, Bigint> divmod(const Bigint& a1, const Bigint& b1) {
    int norm = blockbase / (b1.a.back() + 1);
    Bigint a = a1.abs() * norm;
    Bigint b = b1.abs() * norm;
    Bigint q, r;
    q.a.resize(a.a.size());
    for (int i = a.a.size() - 1; i >= 0; i--) {
      r *= blockbase;
      r += a.a[i];
      int s1 = r.a.size() <= b.a.size() ? 0 : r.a[b.a.size()];
      int s2 = r.a.size() <= b.a.size() - 1 ? 0 : r.a[b.a.size() - 1];
      int d = ((long long)blockbase * s1 + s2) / b.a.back();
      r -= b * d;
      while (r < 0) r += b, d--;
      q.a[i] = d;
    }
    q.sign = a1.sign * b1.sign;
    r.sign = a1.sign;
    q.trim();
    r.trim();
    return make_pair(q, r / norm);
  }
  Bigint operator/(const Bigint& v) const { return divmod(*this, v).first; }
  Bigint operator%(const Bigint& v) const { return divmod(*this, v).second; }
  void operator/=(int v) {
    if (v < 0) sign = -sign, v = -v;
    for (int i = (int)a.size() - 1, rem = 0; i >= 0; i--) {
      long long cur = a[i] + rem * (long long)blockbase;
      a[i] = (int)(cur / v);
      rem = (int)(cur % v);
    }
    trim();
  }
  void operator/=(long long v) { *this /= Bigint(v); }
  Bigint operator/(int v) const {
    Bigint res = *this;
    res /= v;
    return res;
  }
  Bigint operator/(long long v) const {
    Bigint res = *this;
    res /= v;
    return res;
  }
  int operator%(int v) const {
    if (v < 0) v = -v;
    int m = 0;
    for (int i = a.size() - 1; i >= 0; i--)
      m = (a[i] + m * (long long)blockbase) % v;
    return m * sign;
  }
  long long operator%(long long v) const {
    return (*this % Bigint(v)).longValue();
  }
  void operator+=(const Bigint& v) { *this = *this + v; }
  void operator-=(const Bigint& v) { *this = *this - v; }
  void operator*=(const Bigint& v) { *this = *this * v; }
  void operator/=(const Bigint& v) { *this = *this / v; }
  bool operator<(const Bigint& v) const {
    if (sign != v.sign) return sign < v.sign;
    if (a.size() != v.a.size()) return a.size() * sign < v.a.size() * v.sign;
    for (int i = a.size() - 1; i >= 0; i--)
      if (a[i] != v.a[i]) return a[i] * sign < v.a[i] * sign;
    return false;
  }
  bool operator>(const Bigint& v) const { return v < *this; }
  bool operator<=(const Bigint& v) const { return !(v < *this); }
  bool operator>=(const Bigint& v) const { return !(*this < v); }
  bool operator==(const Bigint& v) const {
    return !(*this < v) && !(v < *this);
  }
  bool operator!=(const Bigint& v) const { return *this < v || v < *this; }
  void trim() {
    while (!a.empty() && !a.back()) a.pop_back();
    if (a.empty()) sign = 1;
  }
  bool isZero() const { return a.empty() || (a.size() == 1 && !a[0]); }
  Bigint operator-() const {
    Bigint res = *this;
    res.sign = -sign;
    return res;
  }
  Bigint abs() const {
    Bigint res = *this;
    res.sign *= res.sign;
    return res;
  }
  long long longValue() const {
    long long res = 0;
    for (int i = a.size() - 1; i >= 0; i--) res = res * blockbase + a[i];
    return res * sign;
  }
  friend Bigint gcd(const Bigint& a, const Bigint& b) {
    return b.isZero() ? a : gcd(b, a % b);
  }
  friend Bigint lcm(const Bigint& a, const Bigint& b) {
    return a / gcd(a, b) * b;
  }
  void read(const string& s) {
    sign = 1;
    a.clear();
    int pos = 0;
    while (pos < (int)s.size() && (s[pos] == '-' || s[pos] == '+')) {
      if (s[pos] == '-') sign = -sign;
      pos++;
    }
    for (int i = s.size() - 1; i >= pos; i -= nblock) {
      int x = 0;
      for (int j = max(pos, i - nblock + 1); j <= i; j++)
        x = x * base + s[j] - '0';
      a.push_back(x);
    }
    trim();
  }
  friend istream& operator>>(istream& stream, Bigint& v) {
    string s;
    stream >> s;
    v.read(s);
    return stream;
  }
  friend ostream& operator<<(ostream& stream, const Bigint& v) {
    if (v.sign == -1) stream << '-';
    stream << (v.a.empty() ? 0 : v.a.back());
    for (int i = (int)v.a.size() - 2; i >= 0; i--)
      stream << setw(nblock) << setfill('0') << v.a[i];
    return stream;
  }
  static vector<int> convert_base(const vector<int>& a, int old_digits,
                                  int new_digits) {
    vector<long long> p(max(old_digits, new_digits) + 1);
    p[0] = 1;
    for (int i = 1; i < (int)p.size(); i++) p[i] = p[i - 1] * base;
    vector<int> res;
    long long cur = 0;
    int cur_digits = 0;
    for (int i = 0; i < (int)a.size(); i++) {
      cur += a[i] * p[cur_digits];
      cur_digits += old_digits;
      while (cur_digits >= new_digits) {
        res.push_back(int(cur % p[new_digits]));
        cur /= p[new_digits];
        cur_digits -= new_digits;
      }
    }
    res.push_back((int)cur);
    while (!res.empty() && !res.back()) res.pop_back();
    return res;
  }
  static vector<long long> karatsuba(vector<long long>& a,
                                     vector<long long>& b) {
    int n = a.size();
    vector<long long> res(n << 1);
    if (n <= 32) {
      for (int i = 0; i < n; i++)
        for (int j = 0; j < n; j++) res[i + j] += a[i] * b[j];
      return res;
    }
    int k = n >> 1;
    vector<long long> a1(a.begin(), a.begin() + k);
    vector<long long> a2(a.begin() + k, a.end());
    vector<long long> b1(b.begin(), b.begin() + k);
    vector<long long> b2(b.begin() + k, b.end());
    vector<long long> a1b1 = karatsuba(a1, b1);
    vector<long long> a2b2 = karatsuba(a2, b2);
    for (int i = 0; i < k; i++) a2[i] += a1[i];
    for (int i = 0; i < k; i++) b2[i] += b1[i];
    vector<long long> r = karatsuba(a2, b2);
    for (int i = 0; i < (int)a1b1.size(); i++) r[i] -= a1b1[i];
    for (int i = 0; i < (int)a2b2.size(); i++) r[i] -= a2b2[i];
    for (int i = 0; i < (int)r.size(); i++) res[i + k] += r[i];
    for (int i = 0; i < (int)a1b1.size(); i++) res[i] += a1b1[i];
    for (int i = 0; i < (int)a2b2.size(); i++) res[i + n] += a2b2[i];
    return res;
  }
  Bigint operator*(const Bigint& v) const {
    if ((max(this->a.size(), v.a.size()) * 9 + 5) / 6 <= 8192) {
      int r = 6;
      int t = round(pow(base, r));
      vector<int> ar = convert_base(this->a, nblock, r);
      vector<int> br = convert_base(v.a, nblock, r);
      vector<long long> a(ar.begin(), ar.end());
      vector<long long> b(br.begin(), br.end());
      while (a.size() < b.size()) a.push_back(0);
      while (b.size() < a.size()) b.push_back(0);
      while (a.size() & (a.size() - 1)) a.push_back(0), b.push_back(0);
      vector<long long> c = karatsuba(a, b);
      Bigint res;
      res.sign = sign * v.sign;
      long long carry = 0;
      for (int i = 0; i < (int)c.size(); i++) {
        long long ncarry = c[i] + carry;
        res.a.push_back(ncarry % t);
        carry = ncarry / t;
      }
      while (carry) {
        res.a.push_back(carry % t);
        carry /= t;
      }
      res.a = convert_base(res.a, r, nblock);
      res.trim();
      return res;
    } else {
      vector<int> c = FFT::multiply(this->a, v.a, blockbase);
      Bigint res;
      res.sign = sign * v.sign;
      int carry = 0;
      for (int i = 0; i < (int)c.size(); i++) {
        int ncarry = c[i] + carry;
        res.a.push_back(ncarry % blockbase);
        carry = ncarry / blockbase;
      }
      assert(!carry);
      while (carry) {
        res.a.push_back(carry % blockbase);
        carry /= blockbase;
      }
      res.trim();
      return res;
    }
  }
  friend Bigint sqrt(const Bigint& a) {
    Bigint x0 = a, x1 = (a + 1) / 2;
    while (x1 < x0) {
      x0 = x1;
      x1 = (x1 + a / x1) / 2;
    }
    return x0;
  }
  friend Bigint pow(Bigint a, Bigint b) {
    if (b == Bigint(0)) return Bigint(1);
    Bigint T = pow(a, b / 2);
    if (b % 2 == 0) return T * T;
    return T * T * a;
  }
  friend Bigint pow(Bigint a, int b) { return pow(a, (Bigint(b))); }
  friend int log(Bigint a, int n) {
    int res = 0;
    while (a > Bigint(1)) {
      res++;
      a /= n;
    }
    return res;
  }
  template <class T>
  friend Bigint operator+(const T& v, const Bigint& a) {
    return a + v;
  }
  template <class T>
  friend Bigint operator-(const T& v, const Bigint& a) {
    return -a + v;
  }
  template <class T>
  friend Bigint operator*(const T& v, const Bigint& a) {
    return a * v;
  }
  template <class T>
  friend Bigint operator/(const T& v, const Bigint& a) {
    return Bigint(v) / a;
  }
  Bigint operator++() {
    (*this) += 1;
    return *this;
  }
  Bigint operator++(int) {
    (*this) += 1;
    return *this - 1;
  }
  Bigint operator--() {
    (*this) -= 1;
    return *this;
  }
  Bigint operator--(int) {
    (*this) -= 1;
    return *this + 1;
  }
};
void chemthan() {
  string s;
  cin >> s;
  if (s == "1") {
    cout << 1 << "\n";
    return;
  }
  int st = (int((s).size()) - 1) * (logl(10) / logl(3));
  st = max(0, st - 1);
  Bigint G(s);
  Bigint A = pow(Bigint(3), st);
  int res = INF, cnt = st;
  while (A < G) {
    Bigint T = A;
    for (int i = (0); i < (3 + 1); ++i) {
      if (G <= T) {
        chkmin(res, 3 * cnt + 2 * i);
      }
      T = T * 2;
    }
    A = A * 3;
    cnt++;
  }
  chkmin(res, 3 * cnt);
  cout << res << "\n";
}
int main(int argc, char* argv[]) {
  ios_base::sync_with_stdio(0), cin.tie(0);
  if (argc > 1) {
    assert(freopen(argv[1], "r", stdin));
  }
  if (argc > 2) {
    assert(freopen(argv[2], "wb", stdout));
  }
  chemthan();
  cerr << "\nTime elapsed: " << 1000 * clock() / CLOCKS_PER_SEC << "ms\n";
  return 0;
}
