#include <iostream>
#include <cmath>
#include <vector>
#include <algorithm>
using namespace std;
typedef long long ll;
vector<ll> p;
bool isprime[100001];
ll findprime(ll a) {
	for (int i = 0; i < p.size()&&p[i]*p[i]<=a; i++) {
		if (a%p[i] == 0)	return p[i];
	}
	return a;
}
int main() {
	for (int i = 0; i <= 100000; i++)	isprime[i] = true;
	isprime[0] = isprime[1] = false;
	for (int i = 2; i <= 100000; i++) {
		if (!isprime[i])	continue;
		p.push_back(i);
		for (int j = 2 * i; j <= 100000; j += i)	isprime[j] = false;
	}
	ll l, h;	cin >> l >> h;
	ll ans = 1, out = 1;
	for (ll big = sqrt(h); big >= ans; big--) {
		if (!isprime[big])	continue;
		for (ll another = h / big; another*big >= l; another--) {
			ll small=findprime(another);
			ans = max(ans, small);
			out = (ans == small ? max(out, another*big) : out);
		}
	}
	cout << out << endl;
	return 0;
}