#include <iostream>
#include <vector>
#include <algorithm>
#include <cmath>
#include <queue>
#include <string>
#include <map>
#include <set>
#include <stack>
#include <tuple>
#include <deque>
#include <array>
#include <numeric>
#include <bitset>
#include <iomanip>
#include <cassert>
#include <chrono>
#include <random>
#include <limits>
#include <iterator>
#include <functional>
#include <sstream>
#include <fstream>
#include <complex>
#include <cstring>
#include <unordered_map>
#include <unordered_set>
using namespace std;

using ll = long long;
constexpr int INF = 1001001001;
constexpr int mod = 1000000007;
// constexpr int mod = 998244353;

template<class T>
inline bool chmax(T& x, T y){
    if(x < y){
        x = y;
        return true;
    }
    return false;
}
template<class T>
inline bool chmin(T& x, T y){
    if(x > y){
        x = y;
        return true;
    }
    return false;
}

bool check(int n, ll a, ll b, ll m){
    vector<ll> lower(n + 1), upper(n + 1);
    lower[1] = upper[1] = a;
    lower[2] = upper[2] = b;
    for(int i = 3; i <= n; ++i){
        lower[i] = lower[i - 1] + lower[i - 2] - 1;
        upper[i] = upper[i - 1] + upper[i - 2];
    }
    return lower[n] <= m && m <= upper[n];
}

map<tuple<int, ll, ll, ll>, int> dp;
int func(int n, ll a, ll b, ll m){
    auto key = make_tuple(n, a, b, m);
    if(dp.count(key))   return dp[key];
    if(n == 2){
        if(b == m)  return dp[key] = 0;
        else    return dp[key] = INF;
    }
    if(!check(n, a, b, m))  return dp[key] = INF;

    int res = INF;
    chmin(res, func(n - 1, b, a + b, m));
    chmin(res, func(n - 1, b, a + b - 1, m) + 1);
    return dp[key] = res;
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int n;
    ll m;
    cin >> n >> m;
    int ans = func(n, 1, 1, m);
    if(ans == INF)  ans = -1;
    cout << ans << endl;

    return 0;
}