import java.util.*;
public class Main{
	public static boolean isPrime(int n){
		if(n<2)
			return false;
		for(int i = 2; i<=Math.sqrt(n);i++){
			if(n%i==0)
				return false;
		}
		return true;		
	}



	public static void main(String args[]){
		int i,a,b;
		for(i=10;i<=99;i++){
			a=i%10;
			b=i/10;
			if(isPrime(i)&&isPrime(a*10+b))
				System.out.println(i);
		}
	}
}
/**************************************************************
	Problem: 1513
	User: admin
	Language: Java
	Result: Accepted
	Time:273 ms
	Memory:34368 kb
****************************************************************/