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

int* prime(int k,int n,int *num){
  char *isPrime=(char *)malloc((n+1)*sizeof(char));
  int i;
  for(i=0;i<=n;i++){
    isPrime[i]=1;
  }
  for(i=2;i*i<=n;i++){
    if(isPrime[i]){
      int j;
      for(j=i*i;j<=n;j+=i){
	isPrime[j]=0;
      }
    }
  }
  int len=0;
  for(i=k;i<=n;i++){
    len+=isPrime[i];
  }
  *num=len;
  int *res=(int *)malloc(sizeof(int)*len);
  int j=0;
  for(i=k;i<=n;i++){
    if(isPrime[i]){
      res[j++]=i;
    }
  }
  free(isPrime);
  return res;
}

int digitSum(int n){
  return 1+(n-1)%9;
}

void run(void){
  int k,n;
  scanf("%d%d",&k,&n);

  int len;
  int *p=prime(k,n,&len);

  int maxLen=1;
  int val=0;
  int i;
  for(i=0;i<len;i++){
    int flag=(1<<digitSum(p[i]));
    int k=1;
    while(i+k<len && ((flag>>(digitSum(p[i+k])))&0x01)==0){
      flag|=(1<<digitSum(p[i+k]));
      k++;
    }
    if(k>=maxLen){
      maxLen=k;
      val=p[i];
    }
  }
  printf("%d\n",val);
  free(p);
  return;
}

int main(void){
  run();
  return 0;
}