#include<bits/stdc++.h>
using namespace std;
int f(int n){
	for(int i=2;i*i<=n;i++){
		if(n%i==0){
			return 0;
		}
	}
	return 1;
}
int g(int s){
	int y=0,j=s;
	while(s!=0){
		y*=10;
		y+=s%10;
		s/=10;
	}
	if(y==j) return 1;
	return 0;
}
int main(){
	int a,b;
	scanf("%d",&a);
	scanf("%d",&b);
	for(;a<=b;a++){
		if(f(a)==1){
			if(g(a)==1){
				printf("%d\n",a);
			}
		}
	} 
	return 0;
}
/**************************************************************
	Problem: 1942
	User: houshanglin
	Language: C
	Result: Compile Error
****************************************************************/