#include <iostream>

using namespace std;
int fib(int n)
{
    int a = 0;
    int b = 1;
    while (n-- > 1) {
        int t = a;
        a = b;
        b += t;
    }
    return b;
}
int main()
{   int x,n;
    cin>>x;
    n=0;
    while(fib(n)<x)
        n++;
    cout<<n-1;
   return 0;
}