#include <bits/stdc++.h>
using namespace std;
template <typename T, typename U>
ostream& operator<<(ostream& os, const pair<T, U>& _p) {
  return os << "(" << _p.first << "," << _p.second << ")";
}
template <typename T>
ostream& operator<<(ostream& os, const vector<T>& _V) {
  bool f = true;
  os << "[";
  for (auto v : _V) {
    os << (f ? "" : ",") << v;
    f = false;
  }
  return os << "]";
}
template <typename T>
ostream& operator<<(ostream& os, const set<T>& _S) {
  bool f = true;
  os << "(";
  for (auto s : _S) {
    os << (f ? "" : ",") << s;
    f = false;
  }
  return os << ")";
}
template <typename T, typename U>
ostream& operator<<(ostream& os, const map<T, U>& _M) {
  return os << set<pair<T, U>>(_M.begin(), _M.end());
}
const signed long long INF = 1000000100;
const long double EPS = 1e-9;
int main() {
  ios_base::sync_with_stdio(0);
  signed long long n;
  cin >> n;
  signed long long f0 = 1, f1 = 2, ans = 1;
  while (f0 + f1 <= n) {
    signed long long x = f1;
    f1 += f0;
    f0 = x;
    ans++;
  }
  cout << ans << "\n";
}
