#include <iostream>

using namespace std;
int fib(int n)
{
    if (n <= 1)
        return n;
    else
        return fib(n - 1) + fib(n - 2);
}
int main()
{   int x,n;
    cin>>x;
    n=0;
    while(fib(n)<x)
        n++;
    cout<<n-1;
   return 0;
}