int zshu(int x)
{
	int i;
	for(i=2;i<=sqrt(x);i++)
	{
		if(x%i==0) return 0;
	}
	return x;
}
int main()
{
	int i,len,j,m,n,count;
	char str[100];
	cin>>m>>n;
	if(m%2==0) m++;
	for(i=m;i<n+1;i+=2)
	{
		sprintf(str,"%d",i);
		len=strlen(str);
		if(len%2==0&&i!=11) continue;
		count=0;
		for(j=0;j<len/2;j++)
		{
			if(str[j]==str[len-j-1]) count++;//continue;只是跳过了本次循环 
		}
		if(count==len/2)
		{
			if(zshu(i)!=0) cout<<i<<endl;//比printf快10ms左右 
		}
	}
	return 0;
}