#include <bits/stdc++.h>
using namespace std;
 
#define fi first
#define se second
#define pb push_back
using vi = vector <int>;
using ll = long long;
using pii = pair <int, int>;
//~ const ll mod = 998244353;
const ll mod = 1e9 + 7;
ll qpow(ll a, ll b, ll m = mod) { ll r = 1, t = a;
	for(; b; b /= 2) { if(b & 1) r = r * t % m; t = t * t % m; } return r; }

const int N = 111;
ll f[N];

int main() {
	
	ios :: sync_with_stdio(false);
	
	int n; ll m;
	cin >> n >> m;
	f[1] = f[2] = 1;
	for(int i = 3; i <= n; i ++)
		f[i] = f[i - 1] + f[i - 2];
	
	m = f[n] - m;
	if(m < 0) cout << "-1\n";
	else {
		int ans = 0;
		for(int i = n - 2; i >= 1; i --)
			if(m >= f[i]) {
				m -= f[i];
				ans ++;
			}
		
		if(m != 0) ans = -1;
		cout << ans << '\n';
	}
}