#include <bits/stdc++.h>
#define rep(i, a, n) for(int i = a; i < n; i++)
#define repp(i, n) rep(i, 0, n)
#define repb(i, a, b) for(int i = a; i >= b; i--)
#define all(a) a.begin(), a.end()
#define int long long
using namespace std;

vector<int> prime;
bool isprime[100010];

void sieve(int n){
    rep(i, 0, n + 1) isprime[i] = true;
    isprime[0] = isprime[1] = false;
    rep(i, 2, n + 1){
        if(isprime[i]) prime. push_back(i);
        for(int j = 2*i; j <= n; j += i) isprime[j] = false;
    }
    return;
}

signed main(){
    int l, h, a, ans = -1;
    cin >> l >> h;
    sieve(100000);
    a = prime.back();
    vector<int> cand;

    rep(i, 0, (int)prime.size()){
        int p = h / prime[i];
        while(1){
            if(p < prime[i] || p * prime[i] < l) break;
            bool f = true;
            rep(j, 0, i){
                if(p % prime[j] == 0){
                    f = false; break;
                }
            }
            if(f){
                cand. push_back(prime[i] * p);
                break;
            }
            p--;
        }
    }
    ans = cand.back();
    cout << ans << endl;
}