#include <bits/stdc++.h>
#define GET_MACRO(a, b, c, NAME, ...) NAME
#define rep(...) GET_MACRO(__VA_ARGS__, rep3, rep2)(__VA_ARGS__)
#define rep2(i, a) rep3 (i, 0, a)
#define rep3(i, a, b) for (int i = (a); i < (b); i++)
#define repr(...) GET_MACRO(__VA_ARGS__, repr3, repr2)(__VA_ARGS__)
#define repr2(i, a) repr3 (i, 0, a)
#define repr3(i, a, b) for (int i = (b) - 1; i >= (a); i--)
template<class T1, class T2> inline bool chmin(T1 &a, T2 b) { return b < a && (a = b, true); }
template<class T1, class T2> inline bool chmax(T1 &a, T2 b) { return a < b && (a = b, true); }
using namespace std;
typedef long long ll;

ll F[100];

int main() {
	F[0] = 1;
	F[1] = 1;
	rep (i, 2, 100) F[i] = F[i - 1] + F[i - 2];
	ll N, M;
	cin >> N >> M;
	ll diff = F[N - 1] - M;
	int ans = 0;
	repr (i, N + 1) {
		if (diff - F[i] >= 0) {
			diff -= F[i];
			ans++;
		}
	}
	if (diff != 0) {
		cout << -1 << endl;
	} else {
		cout << ans << endl;
	}
	return 0;
}