#include <bits/stdc++.h>
using namespace std;
using ll = long long;

const ll INF = (ll)1e18;

int main () {
	ios_base::sync_with_stdio(0);
	cin.tie(0); cout.tie(0);
	
	if (fopen ("Tongnn.inp", "r")) {
		freopen ("Tongnn.inp", "r", stdin);
		freopen ("Tongnn.out", "w", stdout);
	}
	
	ll n, m;
	cin >> n >> m;
	// n là ucln
	// m là bcnn
	// n <= a,b <= m
	ll a = 0;
	ll b = 0;
	ll ans = INF;
	
	vector <ll> uoc;
	for (ll i = 2; i * i <= m; i++) {
		if (m % i == 0) {
			uoc.push_back(i);
		}
	}
	
	for (ll i = 0; i < uoc.size(); i++) {
		a = uoc[i];
		b = (m / a) * n;
		ans = min (ans, a + b);
	}
	
	if (ans == INF) {
		cout << -1 << "\n";
	}
	else {
		cout << ans << "\n";
	}
	
	return 0;
}