#include <bits/stdc++.h>

using namespace std;

#define FOR(i,a,b) for(int i=(a);i<(b);i++)
#define REP(i,n) FOR(i,0,n)
#define ALL(v) (v).begin(),(v).end()
#define fi first
#define se second

template<typename A, typename B> inline bool chmax(A &a, B b) { if (a<b) { a=b; return 1; } return 0; }
template<typename A, typename B> inline bool chmin(A &a, B b) { if (a>b) { a=b; return 1; } return 0; }

typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef pair<int, pll> P;

const ll INF = 1ll<<30;
const ll MOD = 1000000007;
const double EPS  = 1e-10;

int main() {
	int n, m;
	cin >> n >> m;
	
	if (n > m) puts("-1");
	else {
		int ans = n;
		if (m % n == 0) chmin(ans, m / n);
		cout << ans << endl;
	}
	return 0;
}