#include <bits/stdc++.h>
using namespace std;
const long long inf = 1e18 + 7;
long long f[105];
long long g[105];
int main() {
  long long n;
  cin >> n;
  f[1] = 2, f[2] = 3;
  g[1] = 2, g[2] = 4;
  for (int h = 3; h <= 100; h++) {
    f[h] = f[h - 1] + f[h - 2];
    g[h] = g[h - 1] + g[h - 1];
    if (f[h] > n) break;
    g[h] = min(g[h], inf);
  }
  long long res = 0;
  for (int h = 1; h <= 100; h++) {
    if (f[h] > n) break;
    if (f[h] <= n && g[h] >= n) res = h;
  }
  cout << res;
  return 0;
}
