#include <bits/stdc++.h>

using namespace std;
#define FOR(i,n) for(int i = 0; i < (n); i++)
#define sz(c) ((int)c.size())
#define ten(n) ((int)1e##n)
using ll = long long;

//素数列挙
bool prime[ten(5)];
vector<ll> prs;
void init_prime() {
	memset(prime, 1, sizeof(prime));
	prime[0] = prime[1] = false;
	for (int i = 2; i < sizeof(prime); i++) if (prime[i])
		for (int j = i * 2; j < sizeof(prime); j += i) prime[j] = false;
	for (int i = 2; i < sizeof(prime); i++) if (prime[i]) prs.push_back(i);
}

ll dv(ll x) {
	for (auto p : prs) if (x % p == 0) return p;
	return x;
}

ll solve(ll l, ll h) {
	for (int i = sz(prs) - 1; i >= 0; i--) {
		if (prs[i] * prs[i] > h) continue;
		for (ll a = h / prs[i]; a * prs[i] >= l; a--) {
			ll x = dv(a);
			if (x >= prs[i]) return prs[i] * a;
		}
	}
	return h - h % 2;
}

int main() {
	init_prime();

	ll l, h; cin >> l >> h;
	ll ans = solve(l,h);
	cout << ans << endl;

	return 0;
}