#include <bits/stdc++.h>
using namespace std;
#define rep(i,a,b) for(int i=a;i<b;i++)
#define rrep(i,a,b) for(int i=a;i>=b;i--)
typedef long long ll;

int N;
ll M;

int solve()
{
	ll dp[81];
	dp[1] = dp[2] = 1;
	rep(i, 3, N + 1) dp[i] = dp[i - 1] + dp[i - 2];

	ll diff = dp[N] - M;
	if (diff < 0) return -1;

	ll sum = 0;
	rep(i, 1, N - 1) sum += dp[i];
	if (sum < diff) return -1;

	int ans = 0;
	rrep(i, N - 2, 1) if(dp[i] <= diff)
	{
		ans++;
		diff -= dp[i];
	}
	return ans;
}

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

	while (cin >> N >> M)
	{
		cout << solve() << endl;
	}
}