#include <cstdio>
#include <algorithm>

using namespace std;

long long fib[512];

int main ()
{
    fib[0] = 0LL;
    fib[1] = 1LL;

    long long x;
    scanf ("%lld", &x);

    if (x == 1LL)
    {
        printf ("0\n");
        return 0;
    }

    int i = 1;
    for (; fib[i] < x - fib[i - 1]; ++i)
        fib[i + 1] = fib[i] + fib[i - 1];

    printf ("%d\n", i);

    return 0;
}