#include <cstdio>
#include <algorithm>

using namespace std;

int main(){

    long long x, a = 0, b = 1, n = 0;

    scanf("%lld", &x);

    while(a < x - b) {
        long long c = a + b;
        a = b;
        b = c;
        ++n;
    }
    printf("%lld", n + 1);

return 0;
}