#include <bits/stdc++.h>

#define mp       make_pair
#define mt	 make_tuple
#define pb       push_back
#define rep(i,n) for(int i=0;i<(n);i++)

using namespace std;

typedef    long long          ll;
typedef    unsigned long long ull;
typedef    pair<int,int>      pii;
typedef    pair<long,long>    pll;

const int INF=1<<29;
const double EPS=1e-9;
const int MOD = 100000007;

const int dx[]={1,0,-1,0},dy[]={0,-1,0,1};
const int MAX_N = 100002;
bool is_prime[MAX_N];
vector<int> primes;
void gen_prime(){
  memset(is_prime, true, sizeof(is_prime));
  is_prime[0] = false;
  is_prime[1] = false;
  for (int i = 2; i < MAX_N; i++){
    if (not is_prime[i])continue;
    primes.push_back(i);
    for (int j = i + i; j < MAX_N; j += i){
      is_prime[j] = false;
    }
  }
  return ;
}
int min_prime_factor(ll x){

  for (const int &val : primes){
    if (val * val > x)break;
    if (x % val == 0){
      return val;
    }
  }
  return x;
}
ll L,H;

ll result;
int main(){

  cin >> L >>H;
  gen_prime();
  result = 0;
  sort(primes.begin(), primes.end());

  for (ll i = primes.size() - 1; i >=0; i--){
    if (primes[i] * primes[i] > H)continue;
    for (ll k = H / primes[i]; k >= primes[i]; k--){
      if ((ll)primes[i] * k >= L){
	ll tmp = min_prime_factor((ll)primes[i] * k);
	if (tmp >= primes[i]){
	  cout << (ll)primes[i] * k << endl;
	  return 0;
	}
      }
    }
  }


}