#include <iostream>
#include <cassert>
#include <cmath>
using namespace std;
typedef long long ll;

int main() {
  ll l, h, an=-1, an2=-1; cin >> l >> h;
  int hh=sqrt(h);
  bool ip[hh+1]; fill(ip, ip+hh+1, false);
  ip[0] = ip[1] = true;
  for(int i=2; i<=hh; i++) {
    if (ip[i]) continue;
    for(int j=2*i; j<=hh; j+=i) ip[j]=true;
  }

  for(ll i=2; i*i<=h; i++) {
    if (ip[i]) continue;
    if (l <= i*i) l = i*i, an=i, an2=i*i;
  }
  //cout << l << " " << h << endl;
  for(ll i=l; i<=h; i++) {
    //if (i%10000==0) cout<<i/10000<<" ";
    for(ll j=2; j*j<=i; j++) {
      //if (ip[j]) continue;
      if (i%j==0) {
        if (j<an) break;
        else {
          an=j; an2=i; break; 
        }
      }
    }
  }
  cout << an2 << endl;
}