#include<bits/stdc++.h>
using namespace std;
bool isPrime(long long j)
{
	for(long long k=2;k<=sqrt(j);k++)
	{
		if(j%k==0) return false;
	}
	return true;
} 
bool isReverse(long long j)
{
	long long temp,backup;
	backup=j;
	while(backup!=0)
	{
		temp=temp*10+backup%10;
		backup/=10;
	}
	if(temp==j) return true;
	else return false;
}
int main()
{
    long long a,b;
    cin>>a>>b;
    for(long long j=a;j<=b;j++)
	{
		if(j%2==0) continue;
		if(isPrime(j)&&isReverse(j)) 	cout<<j<<endl;
	}
	return 0;
}