#include <bits/stdc++.h>
#define rep(i,n) for(int i = 0; i < (n); ++i)
#define srep(i,s,t) for (int i = s; i < t; ++i)
#define drep(i,n) for(int i = (n)-1; i >= 0; --i)
using namespace std;
typedef long long int ll;
typedef pair<int,int> P;
#define yn {puts("Yes");}else{puts("No");}
#define MAX_N 200005

int main() {
    ll n, m;
    cin >> n >> m;
    ll fib[81] = {};
    fib[1] = 1, fib[2] = 1;
    srep(i,3,81){
        fib[i] = fib[i-1] + fib[i-2];
    }

    if(m > fib[n]){
        cout << -1 << endl;
        return 0;
    }

    ll x = fib[n] - m;
    int ans = 0;
    drep(i,n-1){
        if(x == 0)break;
        if(fib[i] <= x){
            x -= fib[i];
            ans++;
        }
    }
    cout << ans << endl;
    return 0;
}