#include<bits/stdc++.h>
#define rep(i,a,b) for(int i=int(a);i<int(b);++i)
using namespace std;
typedef long long ll;
int INF = (1LL << 30) - 1;
int MOD = 1e9+7;
ll N,M;
vector<ll> V;
ll dfs(ll dif,int i){
    if(dif == 0)return 0;
    if(dif >= V[i]){
        return dfs(dif - V[i], i-1) + 1;
    }else{
        return dfs(dif, i-1);
    }
}
main(){
    cin >> N >> M;
    V.resize(N);
    V[0] = V[1] = 1;
    rep(i,2,N)V[i] = V[i-1] + V[i-2];
    ll dif = V[N-1] - M;
    //cout << dif << endl;
    if(dif >= 0)cout << dfs(dif, N-3) << endl;
    else        cout << -1 << endl;
    //V[N-3]までの和でdifを表せるかどうか    
}