#include <algorithm>
#include <iostream>
#include <vector>
#include <map>
using namespace std;

vector<int> getPrimes(int n) {
  vector<bool> isPrime(n+1, true);
  isPrime[0] = isPrime[1] = false;
  for (int i = 2; i * i <= n; i++) {
    if (!isPrime[i])
      continue;
    for (int j = i * i; j <= n; j += i)
      isPrime[j] = false;
  }

  int m = 0;
  for (int i = 0; i <= n; i++)
    if (isPrime[i])
      ++m;

  int pos = 0;
  vector<int> ret(m);
  for (int i = 0; i <= n; i++)
    if (isPrime[i])
      ret[pos++] = i;

  return ret;
}

map<long long, int> factorize(long long n) {
  map<long long, int> ret;
  
  for (long long i = 2; i * i <= n; i++) {
    while (n % i == 0) {
      ++ret[i];
      n /= i;
    }
  }
  
  if (n != 1)
    ret[n] = 1;
  
  return ret;
}

int minFac(long long n) {
  map<long long, int> facs = factorize(n);
  long long ret = facs.begin()->first;
  if (ret == n)
    return 1;
  return (int)ret;
}

int main(int argc, char *argv[])
{
  long long l, h;
  cin >> l >> h;

  vector<int> pr = getPrimes(1e3);
  int n = pr.size();
  pair<int, long long> ret = make_pair(0, 0);
  for (int i = n-1; i >= 0; i--) {
    for (int j = i; j < n; j++) {
      long long x = pr[i] * pr[j];
      if (l <= x && x <= h) {
        ret = max(ret, make_pair(pr[i], x));
      }
    }
    if (ret.first)
      break;
  }

  if (!ret.first) {
    // this block is executed only if abs(h-l) is enough small.
    for (long long i = l; i <= h; i++) {
      ret = max(ret, make_pair(minFac(i), i));
    }
  }
  
  cout << ret.second << endl;
  
  return 0;
}