#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);
*/

    int n = 1;
    long long a = 0, b = 1;
    while(a < x - b)
    {
        long long c = a + b;
        a = b;
        b = c;
        ++n;
    }

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


    return 0;
}