#include<bits/stdc++.h>
using namespace std;
int ds(int a){
	int s = a/10;
	int g = a%10;
	a = g * 10 + s;
}
bool jdss(int a) {
	int s = 0;
	for (int i = 2; i < a; i++) {
		if (a % i == 0) {
			s = 1;
		}
	}
	if (s == 1) {
		return false;
	}
	if (s == 0) {
		return true;
	}
}

signed main() {

	int a, b;
	cin >> a >> b;
	for (int i = a; i <= b; i++) {
		if (jdss(i)&&jdss(ds(i))) {
			cout << i << endl;
		}
	}

	return 0;

}