// yukicoder: 371 ぼく悪いプライムじゃないよ
// 2019.6.17 bal4u

#include <stdio.h>
#include <math.h>

typedef long long ll;
#define MAX  101000
#define SQRT 317
char notPrime[MAX+10] = { 0,0,0,0,1 };			// zero: if prime

void sieve()
{
	int i, j;
	for (i = 3; i <= SQRT; i += 2) {
		if (!notPrime[i]) {
			for (j = i * i; j <= MAX; j += i) notPrime[j] = 1;
		}
	}
}

ll L, H;

int check(int i) {
	int j = (int)(H/i);
	if (!(j & 1)) j--;
	while (j > i && notPrime[j]) j -= 2;
	if (j > i && (ll)i*j >= L) return j;
	return 0;
}

int main()
{
	int i, j, f;
	ll a, ans;

	scanf("%lld%lld", &L, &H);
	ans = H - (H & 1), f = 0;
	if (H <= 8) { printf("%lld\n", ans); return 0; }
	if ((a = H/3*3) == L) { printf("%lld\n", a); return 0; }
	if (a > L && (a & 1)) ans = a;
	
	sieve();
	i = (int)sqrt((double)H);
	if (!(i & 1)) i--;
	j = i + 2;

	f = 0;
	while (i > 2) {
		while (notPrime[i]) i -= 2;
		if (!f && (ll)i*i >= L) ans = (ll)i*i, f = 1;
		if ((j = check(i)) > 0) { ans = (ll)i*j; break; }
		if (f) break;
		i -= 2;
	}
	printf("%lld\n", ans);
	return 0;
}