#include <bits/stdc++.h>

#define show(x) cerr << #x << " = " << x << endl

using namespace std;
using ll = long long;
using pii = pair<int, int>;
using vi = vector<int>;

template <typename T>
ostream& operator<<(ostream& os, const vector<T>& v)
{
    os << "sz=" << v.size() << "\n[";
    for (const auto& p : v) {
        os << p << ",";
    }
    os << "]\n";
    return os;
}

template <typename S, typename T>
ostream& operator<<(ostream& os, const pair<S, T>& p)
{
    os << "(" << p.first << "," << p.second
       << ")";
    return os;
}


constexpr ll MOD = (ll)1e9 + 7;

template <typename T>
constexpr T INF = numeric_limits<T>::max() / 100;

ll mindiv(const ll n)
{
    for (ll i = 2; i * i <= n; i++) {
        if (n % i == 0) {
            return i;
        }
    }
    return 0;
}

int main()
{
    cin.tie(0);
    ios::sync_with_stdio(false);

    ll L, H;
    cin >> L >> H;
    ll sup = 1;
    for (; sup * sup <= H; sup++) {
    }
    sup--;
    vector<bool> isprime(sup, true);
    for (ll i = 2; i <= sup; i++) {
        if (isprime[i]) {
            for (ll j = 2; i * j <= sup; j++) {
                isprime[i * j] = false;
            }
        }
    }
    vector<ll> prime;
    for (ll i = sup; i >= 2; i--) {
        if (isprime[i]) {
            prime.push_back(i);
        }
    }
    ll maxi = 0;
    ll maxnum = 0;
    for (const ll i : prime) {
        if (i < maxi) {
            break;
        }
        const ll sp = H / i;
        for (ll j = sp; j >= i and i * j >= L; j--) {
            const ll d = mindiv(i * j);
            if (maxi < d) {
                maxi = d;
                maxnum = i * j;
            } else if (maxi == d) {
                maxnum = max(maxnum, i * j);
            }
        }
    }
    cout << maxnum << endl;


    return 0;
}