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

typedef long long int64;

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

int64 L, H;
int64 rec(int64 idx, int64 weight, vector< int >& prime, bool first = false)
{
  if(idx >= prime.size() || weight > H) return(2);
  return(max((!first && L <= weight && weight <= H) ? weight : 2LL, max(rec(idx, weight * prime[idx], prime), rec(idx + 1, weight, prime, first))));
}
int main()
{
  vector< int > prime = get_prime(100000);
  cin >> L >> H;
  pair< int64, int64 > ret(2, 2);
  for(int i = 0; i < prime.size(); i++)  {
    int val = rec(i, prime[i], prime, true);
    if(val != 2) ret = max(ret, {prime[i], val});
  }
  cout << ret.second << endl;
}