#define _USE_MATH_DEFINES
#include <algorithm>
#include <cstdio>
#include <functional>
#include <iostream>
#include <cfloat>
#include <climits>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <map>
#include <queue>
#include <random>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <time.h>
#include <vector>
using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> i_i;
typedef pair<ll, int> ll_i;
typedef pair<double, int> d_i;
typedef pair<ll, ll> ll_ll;
typedef pair<double, double> d_d;
typedef pair<int, ll> i_ll;
struct edge { int u, v; ll w; };

double INF = DBL_MAX / 10;
ll MOD = 1000000007;
ll _MOD = 1000000009;
double EPS = 1e-10;

int main() {
	ll lb, ub; cin >> lb >> ub;
	ub++;
	if (ub - lb < 500000) {
		ll ma = 0, ans;
		for (ll x = lb; x < ub; x++)
			for (ll p = 2; p * p <= x; p++)
				if (x % p == 0) {
					if (p >= ma) {
						ma = p;
						ans = x;
					}
					break;
				}
		cout << ans << endl;
	}
	vector<bool> a(100001, true);
	a[0] = a[1] = false;
	for (int i = 2; i <= 100000; i++)
		if (a[i])
			for (int j = i * 2; j <= 100000; j += i)
				a[j] = false;
	vector<int> ps;
	for (int x = 500; x <= 100000; x++)
		if (a[x])
			ps.push_back(x);
	ll ans;
	for (ll p: ps)
		if (lb <= p * p && p * p < ub)
			ans = p * p;
	cout << ans << endl;
}