# include<iostream>
# include <cstring>
#include<math.h>
using namespace std;

int zs(int n){
	for(int i=2;i*i<=n;i++){
		if(n%i==0) return 0;
	}
	return 1;
}

int hw(int num){
	int t=num,ans=0;
	while(t){
		ans = ans*10 + t%10;
		t/=10;
	}

	if(num==ans) return 1;
	else return 0;
}

int main()
{	
	int a,b;
	cin >> a >> b;
	for(int i=a;i<=b;i+=2){
		if(zs(i)){
			if(hw(i)){
				cout << i << endl;
			}
		}
	}
	
    return 0;
 }