//uso

#include <iostream>
#include <string>
#include <vector>
#include <cmath>
#include <algorithm>
#include <cstdlib>
#include <ctime>
#include <cstdio>
#include <functional>
#include <set>
#include <sstream>
#include <map>
#include <queue>
#include <stack>

using namespace std;

const long long mod=1000000007; 

const int N=50000;

int main()
{

	long long l,r;
	cin>>l>>r;
	
	vector<long long> primes;
	vector<bool> is_prime(N+1,true);
	is_prime[0]=is_prime[1]=false;
	for(long long i=2;i<N+1;i++){
		if(!is_prime[i]) continue;
		primes.push_back(i);
		for(int j=2LL*i;j<N+1;j+=i) is_prime[j]=false;
	}
	//cout<<primes.size()<<endl;

	vector<long long> p2;
	for(int i=0;i<primes.size();i++){
		for(int j=i+1;j<primes.size();j++) p2.push_back(primes[i]*primes[j]);
		p2.push_back(primes[i]*primes[i]);
	}
	sort(p2.begin(),p2.end());
	
	auto pos=upper_bound(p2.begin(),p2.end(),r);
	pos--;
	cout<<*pos<<endl;

	return 0;
}