#include <stdio.h>
#include <stdlib.h>
#include <math.h>

//minimum prime
long func(long a){
  long result;
  long i;
  
  if(a%2==0) return 2;
  else{
    for(i=3;i<=sqrt(a);i+=2){
      if(a%i==0)
	return i;
    }
  }
  return a;
}

long max (long a , long b){
  long result;
  (a>b)?(result = a):(result = b);
  return result;
}
int main(){
  long  a,L,H,i,j,prime[100000];
  long result,result_prime;
  int num=0;


  scanf("%ld %ld",&L,&H);
  for(a=2;a<=sqrt(H);a++){
    if(a==func(a)){
      prime[num]=a;
      num++;
    }
  }
  for(i=num-1;i>=0;i--){
    if(prime[i]*prime[i]<=H){
      for(a=H/prime[i]*prime[i];a>=max(L,prime[i]*prime[i]);a-=prime[i]){
	for(j=0;j<i;j++){
	  if(a%prime[j]==0)break;
	}
	if(j==i) {
	  printf("%ld\n",a);
	  return 0;
	}
      }
    }
  }
  
  return 0;
}