/*
                   _ooOoo_
                  o8888888o
                  88" . "88
                  (| -_- |)
                  O\  =  /O
               ____/`---'\____
             .'  \\|     |//  `.
            /  \\|||  :  |||//  \
           /  _||||| -:- |||||-  \
           |   | \\\  -  /// |   |
           | \_|  ''\---/''  |   |
           \  .-\__  `-`  ___/-. /
         ___`. .'  /--.--\  `. . __
      ."" '<  `.___\_<|>_/___.'  >'"".
     | | :  `- \`.;`\ _ /`;.`/ - ` : | |
     \  \ `-.   \_ __\ /__ _/   .-` /  /
======`-.____`-.___\_____/___.-`____.-'======
                   `=---='
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
            pass System Test!
*/
#include <bits/stdc++.h>
using namespace std;

template <typename T>
std::ostream &operator<<(std::ostream &out, const std::vector<T> &v) {
  if (!v.empty()) {
    out << '[';
    std::copy(v.begin(), v.end(), std::ostream_iterator<T>(out, ", "));
    out << "\b\b]";
  }
  return out;
}
template <typename T1, typename T2>
std::ostream &operator<<(std::ostream &out, const std::pair<T1, T2> &p) {
  out << "[" << p.first << ", " << p.second << "]";
  return out;
}
template <class T, class U>
void chmin(T &t, U f) {
  if (t > f) t = f;
}
template <class T, class U>
void chmax(T &t, U f) {
  if (t < f) t = f;
}
template <typename T>
void uniq(vector<T> &v) {
  v.erase(unique(v.begin(), v.end()), v.end());
}

vector<int> eratosthenes(int N) {
  vector<bool> is_prime(N + 1, true);
  vector<int> primes;
  is_prime[0] = false;
  is_prime[1] = false;
  for (int i = 2; i <= N; ++i)
    if (is_prime[i]) {
      primes.push_back(i);
      for (int j = i * 2; j <= N; j += i) {
        is_prime[j] = false;
      }
    }
  return primes;
}

int64_t L, H;
vector<int> primes;

int64_t dfs_check(int64_t d, int pos) {
  if (L <= d && d <= H) return d;
  int64_t ans = -1;
  for (int i = pos; i < primes.size(); ++i) {
    if (d * primes[i] > H) break;
    chmax(ans, dfs_check(d * primes[i], i));
  }
  return ans;
}

int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  primes = eratosthenes(1e6);
  cin >> L >> H;

  int64_t ans = 0;
  for (int i = 0; i < primes.size(); ++i) {
    int64_t d = dfs_check(primes[i], i);
    if (d > primes[i]) ans = d;
  }
  assert(ans > 0);
  cout << ans << endl;
}