/**
 *   @FileName	a.cpp
 *   @Author	kanpurin
 *   @Created	2020.05.26 02:18:13
**/

#include "bits/stdc++.h" 
using namespace std; 
typedef long long ll;

int main() {
    int n;cin >> n;
    ll m; cin >> m;
    vector<ll> a(n);
    a[0] = 1;
    a[1] = 1;
    for (int i = 2; i < n; i++) {
        a[i] = a[i-1] + a[i-2];
    }
    if (a[n-1] < m) {
        cout << -1 << endl;
    }
    else if (a[n-1] == m) {
        cout << 0 << endl;
    }
    else {
        int ans = 0;
        m = a[n-1] - m;
        for (int i = n-1; i >= 0; i--) {
            if (a[i] <= m) {
                m -= a[i];
                ans++;
            }
        }
        if (m == 0) {
            cout << ans << endl;
        }
        else {
            cout << -1 << endl;
        }
    }
    return 0;
}