#include <bits/stdc++.h>
using namespace std;

bool JudgePrime(int num) {
	if (num == 1) return false;
	for (int i = 2; i * i <= num; i++) {
		if (num % i == 0) return false;
	}
	return true;
}

bool isPalindrome(int num) {
	int original = num;
	int reversed = 0;

	while (num > 0) {
		int digit = num % 10;
		reversed = reversed * 10 + digit;
		num /= 10;
	}

	return original == reversed;
}

int main() {
	long long a, b;
	cin >> a >> b;

	if (b > 9999999)b = 9999999;
	if (a % 2 == 0)a++;
	if (a < 2)printf("2\n");
	for (int i = a; i <= b; i += 2) {
		if ((1000 <= i && i <= 9999) || (100000 <= i && i <= 999999)) continue;
		if (JudgePrime(i) == 1 && isPalindrome(i) == 1)printf("%d\n",i);
	}

	return 0;
}