/*
ID: mytbk921
LANG: C
TASK: pprime
*/

#include <stdio.h>
#include <stdlib.h>

static int sqrmod(int b, int n)
{
	long long t = b;
	t *= t;
	return t % n;
}

int expmod(int b, int e, int n)
{
	long long t;
	if (e == 0)
		return 1;

	t = expmod(b, e/2, n);
	t = sqrmod(t, n);
	if (e%2) {
		t *= b;
		t %= n;
	}

	return t;
}

int mr_test(int test, int n)
{
	int s, r;
	long long t;
	r = 0;
	for (s = n-1; s%2==0; s/=2)
		r++;
	t = expmod(test, s, n);
	if (t==1)
		return 1;
	while (r--) {
		if (t==n-1)
			return 1;
		t = sqrmod(t, n);
	}
	return 0;
}

/* Miller-Rabin test:
 * return 1 if considered prime,
 * otherwise return the proof of non-prime
 */
int miller_rabin(const int n)
{
	int r;
	int i;

	if (n==2 || n==3 || n==5 || n==7)
		return 1;

	if (n%2==0 || n==1)
		return 0;

	for (i=0; i<100; i++) {
		do {
			r = rand() % n;
		} while (r==0 || r==1 || r==n-1);
		if (!mr_test(r, n))
			return r;
	}
	return 1;
}

int make_palindrome(int half, int odd)
{
	int s = half;
	int r = (odd)?half/10:half;
	while (r) {
		s = s*10+(r%10);
		r /= 10;
	}
	return s;
}

int main()
{
	FILE *fin, *fout;
	int a, b;
	int i,j;
	int base, base_max;
	int stopped = 0;

	fin = fopen("pprime.in", "r");
	fout = fopen("pprime.out", "w");

	fscanf(fin, "%d%d", &a, &b);

	for (base=1; make_palindrome(base, 1)<a; base*=10)
		;
	base /= 10;

	while (!stopped) {
		base_max = base*10-1;
		for (j=1; j>=0; j--) {
			for (i=base; i<=base_max; i++) {
				int t = make_palindrome(i, j);
				if (t<a)
					continue;
				if (t>b) {
					stopped = 1;
					break;
				}
				if (miller_rabin(t) == 1)
					fprintf(fout, "%d\n", t);
			}
		}
		base *= 10;
	}

	fclose(fout);
	return 0;
}