#include <cstdio>
#include <cstdlib>
using namespace std;

bool prime[10000005]={};
void ai ();
bool palin(int x);

int main () {
	int a,b;
	scanf ("%d%d",&a,&b);
	ai();
	
	if (a%2==0) a++;
	for (int i=a;i<=b;i+=2){
		palin(i);
		if (prime[i]&&palin(i)&&i<10000000) printf ("%d\n",i);
	}
	
	return 0;
} 


void ai(){
	for (int i=1;i<=10000000;i++) prime[i]=1;
	for (int i=2;i<=10000000;i++)
		if (prime) for (int j=i*2;j<=10000000;j+=i)
				prime[j]=0; 
	
}
bool palin (int x){
	int y=x,z=0;
	while (y!=0){
		z=z*10+y%10;
		y=y/10;
	}
	if (z==x) return 1;
	else return 0;
}