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

int main() {
	long long L, H;
	cin >> L >> H;

	const int N = 2e5 + 100;
	vector<long long> primes;
	vector<char> is_prime(N, true);

	for (int i = 2; i < N; i++) {
		if (is_prime[i]) {
			primes.push_back(i);
			for (int j = i * 2; j < N; j += i) {
				is_prime[j] = false;
			}
		}
	}

	if (H - L <= 200200) {
		pair<long long, long long> ans;
		for (long long i = L; i <= H; i++) {
			long long p = 1;
			for (int j = 0; j < primes.size(); j++) {
				if (i % primes[j] == 0) {
					if (i != primes[j]) p = primes[j];
					break;
				}
			}
			if (p != 1) ans = max(ans, make_pair(p, i));
		}
		cout << ans.second << endl;
		return 0;
	}

	for (int i = primes.size() - 1; i >= 0; i--) {
		long long cand = primes[i] * primes[i];
		if (L <= cand && cand <= H) {
			cout << cand << endl;
			return 0;
		}
	}
	cout << "fail" << endl;
}