include <bits/stdc++.h>

using namespace std;

int main() {

int a, b;
scanf("%d%d", &a, &b);
if (a == 2)
	printf("%d\n", a);
if (a % 2 == 0)
	a += 1;
for (int n = a; n <= b; n += 2) {
	int r = 0, t = n;
	while (t)
		r = r * 10 + t % 10, t /= 10;
	if (n != r)
		continue;
	bool p = n > 1;
	for (int i = 2; i * i <= n && p; p = n % i++);
	if (p)
		printf("%d\n", n);
}
return 0;

}