#include <bits/stdc++.h>
using namespace std;
const int N = 1e6 + 500;
long long dp[N];
long long n;
void init() {
  dp[0] = 1ll;
  dp[1] = 2ll;
  for (int i = 2; i < N; i++) {
    dp[i] = dp[i - 2] + dp[i - 1];
  }
}
int main() {
  init();
  while (cin >> n) {
    int cur = 0;
    while (dp[cur] <= n) cur++;
    cout << cur - 1 << endl;
  }
  return 0;
}
