#define  _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <algorithm>
#include <utility>
#include <functional>
#include <cstring>
#include <queue>
#include <stack>
#include <math.h>
#include <iterator>
#include <vector>
#include <string>
#include <set>
#include <math.h>
#include <iostream> 
#include<map>
#include <iomanip>
#include <stdlib.h>
#include <list>
#include <typeinfo>
#include <list>
#include <set>
using namespace std;
#define MAX_MOD 1000000007
#define REP(i,n) for(long long i = 0;i < n;++i)
#define LONG_INF 100000000000000
long long fib[100] = {};
int main() {
	long long n, m;
	cin >> n >> m;
	fib[1] = 1;
	fib[2] = 1;
	for (int i = 3;i <= n;++i) {
		fib[i] = fib[i - 1] + fib[i - 2];
	}
	if (fib[n] < m) {
		cout << -1 << endl;
		return 0;
	}
	long long dis = fib[n] - m;
	int ans = 0;
	for (int i = n-2;i > 0;--i) {
		if (dis >= fib[i]) {
			dis -= fib[i];
			ans++;
		}
	}
	if (dis != 0) {
		cout << -1 << endl;
		return 0;
	}
	cout << ans << endl;
	return 0;
}