#include<iostream>
using namespace std;
int a,b;
int huiwen(int a){
	int b[10];
	int hu = 0;
	while(a != 0){
		b[hu] = a % 10;
		hu++;
		a = a / 10;
	}
	for(int i = 0;i <= hu / 2;i++){
		if(b[i] != b[hu - i - 1]){
			return 0;
		}
	}
	return 1;
}
int zhishu(int a){
	for(int i = 3;i < a / 2;i++){
		if(a % i == 0){
			return 0;
		}
	}
	return 1;
}
int main(){
	cin>>a>>b;
	if(a % 2 == 0){
		a++;
	}
	for(int i = a;i <= b;i+=2){
		if(huiwen(i)){
			if(zhishu(i)){
				cout<<i<<endl;
			}
		}
	}
}