#include <iostream>
#include <string>
#include <algorithm>
#include <vector>
#include <iomanip>
#include <cmath>
#include <stdio.h>
#include <queue>
#include <deque>
#include <cstdio>
#include <set>
#include <map>
#include <bitset>
#include <stack>
#include <cctype>
using namespace std;
long long fib[88];
bitset<70> bit;
int main() {
	long long n, m;
	cin >> n >> m;
	fib[1] = 1;
	fib[2] = 1;
	for (int i = 3; i <= 81; i++) {
		fib[i] = fib[i - 1] + fib[i - 2];
	}
	if (fib[n] < m) {
		cout << "-1" << endl;
	}
	else {
		long long n1 = fib[n] - m;
		int co = 0;
		for (int i = n-2; i > 0; i--) {
			if (n1 >= fib[i]) {
				n1 -= fib[i];
				co++;
			}
		}
		cout << co << endl;
	}
}