#include <iostream>
#include <algorithm>
#include <vector>
#include <cmath>
using namespace std;


inline long long min_prime_check(long long x) {
	if (x % 2 == 0) return 2;
	for (long long i = 3; i*i <= x; i += 2) {
		if (x % i == 0)return i;
	}
	return x;
}

int main() {
	cin.tie(0); ios::sync_with_stdio(false);

	long long L, H; cin >> L >> H;
	vector<long long> p;

	/* initialize*/
	long long Sq = (int)sqrt(H);

	for (long long i = Sq; i >= 3; i--) {
		if (i == min_prime_check(i) ) {
			p.push_back(i);
		}
	}
	p.push_back(2);

	/* solve */
	long long l, h;

	for (long long i = 0; i < p.size(); i++) {
		l = L / p[i]; h = H / p[i];
		for (long long j = h; j >= l; j--) {
			if (min_prime_check(j) >= p[i]) {
				if (L <= j * p[i] && H >= j*p[i]) {
					cout << j*p[i] << endl; return 0;
				}
			}
		}
	}
}