#define _USE_MATH_DEFINES
#include <cstdio>
#include <iostream>
#include <sstream>
#include <fstream>
#include <iomanip>
#include <algorithm>
#include <cmath>
#include <complex>
#include <string>
#include <vector>
#include <list>
#include <queue>
#include <stack>
#include <set>
#include <map>
#include <bitset>
#include <numeric>
#include <limits>
#include <climits>
#include <cfloat>
#include <functional>
using namespace std;

void findPrime(int N, vector<bool>& isPrime)
{
    isPrime.assign(N+1, true);
    isPrime[0] = isPrime[1] = false;
    for(int i=2; i*i<=N; i++){
        if(isPrime[i]){
            for(int j=i; i*j<=N; j++){
                isPrime[i*j] = false;
            }
        }
    }
}

int main()
{
    vector<bool> isPrime;
    findPrime(100000, isPrime);

    vector<long long> prime;
    for(int i=0; i<=100000; ++i){
        if(isPrime[i])
            prime.push_back(i);
    }

    long long a, b;
    cin >> a >> b;

    for(long long x=100000; ; --x){
        if(!isPrime[x])
            continue;

        for(long long y=b/x; y>=x && y*x>=a; --y){
            bool ok = true;
            for(long long p : prime){
                if(p >= x || p * p > y)
                    break;
                if(y % p == 0){
                    ok = false;
                    break;
                }
            }

            if(ok){
                cout << (x * y) << endl;
                return 0;
            }
        }
    }
}