#define _CRT_SECURE_NO_WARNINGS
#define _USE_MATH_DEFINES

#include "bits/stdc++.h"
#define REP(i,a,b) for(i=a;i<b;++i)
#define rep(i,n) REP(i,0,n)
#define ll long long
#define ull unsigned ll
typedef long double ld;
#define ALL(a) begin(a),end(a)
#define ifnot(a) if(not a)
#define dump(x)  cerr << #x << " = " << (x) << endl
using namespace std;

// #define int ll
bool test = 0;
int dx[] = { 0,1,0,-1 };
int dy[] = { 1,0,-1,0 };
#define INF (1 << 28)
ull mod = (int)1e9 + 7;
//.....................
#define MAX (int)1e6 + 5

string manth_name = "9";

/* Eratosthenes(T prime[],int n)は
nまでの素数をprimeに、2,3,と入れていきます */
/* 実行後arr[i]はiが素数の時1になります */
int prime[MAX + 5];
int isprime[MAX + 5];
int prime_size = 0;

void Eratosthenes(int N) {
	for (int i = 0; i < N; i++) {
		isprime[i] = 1;
	}
	for (int i = 2; i < sqrt((double)N); i++) {
		if (isprime[i]) {
			for (int j = 0; i * (j + 2) < N; j++) {
				isprime[i *(j + 2)] = 0;
			}
		}
	}
	for (int i = 2; i < N; i++) {
		if (isprime[i]) {
			prime[prime_size++] = i;
		}
	}
}

ll min_prime_factor(ll n) {
	ll i;
	for (i = 2; i*i <= n; i++) {
		if (n % i == 0) return i;
	}
	return n;
}

signed main(void) {
	ll i, j, k;
	ll L, H;
	cin >> L >> H;
	Eratosthenes((int)sqrt(H) + 5);
	for (i = prime_size - 1; i > -1; i--) {
		for (j = H/prime[i]*prime[i]; j > 1; j -= prime[i]) {
			if (j < L) break;
			if (min_prime_factor(j) == prime[i]) {
				cout << j << endl;
				return 0;
			}
		}
	}
}