#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
//#include<cctype>
#include<climits>
#include<iostream>
#include<string>
#include<vector>
#include<map>
//#include<list>
#include<queue>
#include<deque>
#include<algorithm>
//#include<numeric>
#include<utility>
#include<complex>
//#include<memory>
#include<functional>
#include<cassert>
#include<set>
#include<stack>

const int dx[] = {1, 0, -1, 0};
const int dy[] = {0, 1, 0, -1};
using namespace std;
typedef long long ll;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef pair<int, int> pii;

ll fib[82];

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    int N;
    ll M;
    cin >> N >> M;
    N--;
    fib[0] = fib[1] = 1;
    for (int i = 2; i < 80; i++) {
        fib[i] = fib[i-1] + fib[i-2];
    }
    if (fib[N] < M) {
        cout << -1 << endl;
        return 0;
    }
    ll diff = fib[N]-M;
    int ans = 0;
    while (diff) {
        int index = upper_bound(fib, fib+80, diff) - fib - 1;
        if (N-index <= 1) {
            cout << -1 << endl;
            return 0;
        }
        ans++;
        diff -= fib[index];
    }
    cout << ans << endl;
    return 0;
}