#include <iostream>
using namespace std;

int main() {
    long long x;
    cin >> x;
    
    if (x == 1) {
        return 0;
    }
    
    int ans = 1;
    long long a = 0, b = 1;
    while (a < x - x) {
        long long aux = b;
        b += a;
        a = aux;
        ans += 1;
    }
    cout << ans;
}