#include <iostream>

using namespace std;
int main()
{
    int x;
    cin >> x;
    
    int prev = 0;
    int aux = 0;
    int fibonacciValue = 1;
    int currentFibonacciNumber = 1;

    while (fibonacciValue < x) {
        aux = fibonacciValue;
        fibonacciValue += prev;
        prev = aux;
        currentFibonacciNumber++;
    }

    cout << currentFibonacciNumber-1;

    return 0;
}