#include <bits/stdc++.h>
using namespace std;
using ll = long long;

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    ll L, R;
    cin >> L >> R;
    int m = 100000;
    const int INF = 1 << 30;
    vector<int> tb(m + 1, INF), p;
    tb[0] = tb[1] = 0;
    for(int i = 2; i <= m; i++){
        if(tb[i] != INF) continue;
        p.emplace_back(i);
        for(int j = i; j <= m; j += i) tb[j] = min(tb[j], i);
    }
    auto f = [&](ll v){
        for(auto &&v2 : p){
            if(v % v2 == 0) return v2;
        }
        return INF;
    };
    ll ans = 0, mn_prime = -1;
    for(ll i = min(m, int(sqrt(R) + 1)); i >= 2 && i >= mn_prime; i--){
        if(tb[i] < mn_prime) continue;
        ll bl = max(mn_prime, (L + i - 1) / i);
        for(ll j = R / i; j >= bl; j--){
            ll v = f(j);
            if(tb[i] < v) v = tb[i];
            if(v > mn_prime){
                mn_prime = v;
                ans = i * j;
            }else if(v == mn_prime){
                ans = max(ans, i * j);
            }
        }
    }
    cout << ans << '\n';
}