#include<algorithm>
#include<complex>
#include<ctype.h>
#include<iomanip>
#include<iostream>
#include<fstream>
#include<map>
#include<math.h>
#include<numeric>
#include<queue>
#include<set>
#include<stack>
#include<stdio.h>
#include<string>
#include<string>
#include<vector>

using namespace std;
typedef long long ll;

#define FOR(i,a,b) for(ll i=(a);i<(b);++i)
#define ALL(v) (v).begin(), (v).end()
#define p(s) cout<<(s)<<endl
#define p2(s, t) cout << (s) << " " << (t) << endl
#define br() p("")
#define pn(s) cout << (#s) << " " << (s) << endl
#define p_yes() p("Yes")
#define p_no() p("No")

const ll mod = 1e9 + 7;
const ll inf = 1e18;

template < typename T >
void vprint(T &V){
	for(auto v : V){
    	cout << v << " ";
	}
	cout << endl;
}

int main(){
    cin.tie(0);
    ios::sync_with_stdio(false);

    // input
    ll N, M;
    cin >> N >> M;

    vector<ll> A(N);
    A[0] = 1;
    A[1] = 1;
    FOR(i, 2, N){
        A[i] = A[i-1] + A[i-2];
    }

    if(M==A[N-1]){
        p(0);
        return 0;
    }

    if(M>A[N-1]){
        p(-1);
        return 0;
    }

    ll D = A[N-1] - M;
    ll count = 0;
    for(int i=N-3; i>=0; i--){
        if(D >= A[i]){
            D -= A[i];
            count++;
        }
    }
    p(count);
    
    return 0;
}