#include<bits/stdc++.h>
using namespace std;
bool ttt(int i)
{
	if(i<=2) return 0;
	else
	{
		int s=2;
		while(s*s<=i)
		{
			if(i%s==0) return 0;
			s++;
		}
	}
  return 1;
}
int main()
{
	int a,b,mid,len,next,ans;
	cin>>a>>b;
	for(int i=a;i<=b;i++)
	{
		int t=0,s=i;
		if(i<=9&&ttt(i))
		cout<<i<<"\n";
		else if(i%10!=0)
		{
			while(s/=10)
			{
				t++;
			}
			s=i;
			ans=1;
			while(t>=ans)
			{
				
				len=pow(10,ans);
				next=pow(10,t);
				if(s%len!=s/next)
				{
					break;
				}
				t--;
				ans++;
			}
			if(t>=ans)
			continue;
			else if(ttt(i)) cout<<i<<"\n";
		}
	}
}