#include "bits/stdc++.h"
#include<unordered_map>
#include<unordered_set>
#pragma warning(disable:4996)
using namespace std;
using ld = long double;
template<class T>
using Table = vector<vector<T>>;

long long int fib[80];
int main() {
	long long int N, M; cin >> N >> M;
	fib[0] = 1;
	fib[1] = 1;
	for (int i = 2; i < 80; ++i) {
		fib[i] = fib[i - 1] + fib[i - 2];
	}
	long long int rest = fib[N - 1]-M;

	int ans = 0;
	for (int i = N - 3; i >= 0; --i) {
		if (fib[i] <= rest) {
			rest -= fib[i];
			ans++;
		}
	}
	if (rest)ans = -1;
	cout << ans << endl;
	return 0;
}