#include<bits\stdc++.h>
using namespace std;
bool ss(long long a)
{
	if(a<2) return 0;
	for(int i=2;i<=sqrt(a);i++)
	{
		if(a%i==0) return 0;
	}
	return 1;
 } 
bool hws2(long long a)
{
	long long b=0,c=a;
	while(a!=0)
	{
		b=b*10+a%10;
		a/=10;
	}
	if(b==c) return 1;
	return 0;
}
bool hws1(long long a)
{
	int b;
	while(a!=0)
	{
		b++;
		a/=10;
	}
	return b%2;
}
int aa(long long a)
{
	int b=1;
	while(a!=0)
	{
		a/=10;
		b*=10;
	}
	return b/10;
}
int main()
{
	long long a,b;
	cin>>a>>b;
	if(a<=2)
	{
		cout<<"2"<<endl;
		a=3;
	}
	else
	{
		a+=a%2-1;
	}
	for(long long j=aa(a);j<b;j*=10)
	{
		if(j==0) j++;
		else if(j==10) cout<<11<<endl;
		else if(hws1(j))
		{
			for(long long i=j+1;i<=j*10;i+=2)
			{
				if(i!=11&&hws1(i)) a=a;
				else if(ss(i)&&hws2(i)) cout<<i<<endl;
			}
		}
	}
	return 0;
}