#include <iostream>
using namespace std;
int main() {
	cin.tie(0); ios::sync_with_stdio(false);
	long long dp[81] = { 0 },N, M, dif, count = 0;
	dp[1] = 1; dp[2] = 1; cin >> N >> M;
	for (int i = 3; i <= N; i++) {	dp[i] = dp[i - 1] + dp[i - 2];	}
	dif = dp[N] - M;
	if (dif < 0) { cout << -1 << endl; return 0; }
	for (int i = N - 2; i > 0; i--) {
		if (dp[i] <= dif) {
			dif -= dp[i];count++;
			if (dif == 0) { cout << count << endl; return 0; }
		}
	}
	cout << count << endl;
	return 0;
}