#include <iostream>
#include <queue>
#include <map>
#include <list>
#include <vector>
#include <string>
#include <limits>
#include <cassert>
#include <fstream>
#include <cstring>
#include <bitset>
#include <iomanip>
#include <algorithm>
#include <functional>
#include <cstdio>
#include <ciso646>
#include <array>

using namespace std;

#define FOR(i,a,b) for (int i=(a);i<(b);i++)
#define RFOR(i,a,b) for (int i=(b)-1;i>=(a);i--)
#define REP(i,n) for (int i=0;i<(n);i++)
#define RREP(i,n) for (int i=(n)-1;i>=0;i--)

#define inf 0x3f3f3f3f
#define CLEAR(a) a = decltype(a)()
#define MP make_pair
#define ALL(a) (a).begin(),(a).end()
#define pii pair<int ,int>
#define pcc pair<char,char>
#define pic pair<int,char>
#define pci pair<char,int>
#define VS vector<string>
#define VI vector<int>
#define DEBUG(x) cout<<#x<<": "<<x<<endl
#define pi 2*acos(0.0)
#define INFILE() freopen("in.txt","r",stdin)
#define OUTFILE() freopen("out.txt","w",stdout)
#define ll long long
#define ull unsigned long long
#define eps 1e-14

vector<ull> prime;
ull L, H;

// 素因数分解した最小値を求める 
bool GetFac(ull index, ull num) {
	for (int i = index+1; i < prime.size(); ++i) {
		if (num % prime[i] == 0) return false;
	}
	return true;
}

int main(void) {
	ull L, H; cin >> L >> H;
	ull ma = sqrt(H)+1;
	bitset<100005> b;
	b.flip();

	int sqrtMax = ma;
	for (int i = 2; i < sqrtMax; ++i) {
		if (b[i]) {
			prime.push_back(i);
			for (int j = 2; i*j < sqrtMax; ++j) {
				b[i*j] = false;
			}
		}
	}

	reverse(ALL(prime));

	ull res = -1;
	for (ull i = 0; i < prime.size(); ++i) {
		ull p = prime[i];
		for (ull j = H/p; j >= p; --j) {
			if (p*j < L) break;
			if (GetFac(i, j)) {
				cout << p*j << endl;
				return 0;
			}
		}
	}

	return 0;
}