#include <iostream>
#include <iomanip>
#include <vector>
#include <algorithm>
#include <numeric>
#include <functional>
#include <cmath>
#include <queue>
#include <stack>
#include <set>
#include <map>
#include <sstream>
#include <string>
#define repd(i,a,b) for (int i=(int)(a);i<(int)(b);i++)
#define rep(i,n) repd(i,0,n)
#define all(x) (x).begin(),(x).end()
#define mod 1000000007
#define inf 2000000007
#define mp make_pair
#define pb push_back
typedef long long ll;
using namespace std;
template <typename T>
inline void output(T a, int p) {
    if(p) cout << fixed << setprecision(p)  << a << "\n";
    else cout << a << "\n";
}
// end of template

ll s_prime(ll a){
    if(a % 2 == 0) return 2;
    for(ll i = 3; i * i <= a; i += 2){
        if(a % i == 0) return i;
    }
    return a;
}

bool is_prime(ll a){
    return s_prime(a) == a;
}

int main() {
    cin.tie(0);
    ios::sync_with_stdio(0);
    // source code
    ll L, H;
    cin >> L >> H;
    
    ll sqrtH = 2;
    while(1){
        if(sqrtH * sqrtH > H)break;
        sqrtH++;
    }

    // j: 素数 i: 最小の素因数がj以上ならばOK
    for(ll j = sqrtH; j >= 2; j--){
        for(ll i = H / j; i >= j; i--){
            if(!is_prime(j) || j * i < L) break;
            if(s_prime(i) >= j) {
                output(i * j, 0);
                return 0;
            }
        }
    }
    
    
    
    
    return 0;
}