#include <bits/stdc++.h>
using namespace std;
using ll = long long;

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    ll n, m, ans = 1ll << 62;
    cin >> n >> m;
    vector<ll> a(n);
    a[0] = a[1] = 1;
    for(int i = 2; i < n; i++){
        a[i] = a[i - 1] + a[i - 2];
    }
    auto f = [&](ll v){
        ll res = 0;
        for(int i = n - 3; i >= 0; i--){
            if(v >= a[i]){
                v -= a[i];
                res++;
            }
        }
        return v == 0 ? res : -1;
    };
    cout << f(a.back() - m) << '\n';
}