#include<iostream>
using namespace std;
bool judge1(int a)
{
	int m = 0, arr[20];
		while (a)
	{
			arr[m] = a % 10;
			a /= 10;
			m++;	
		}
		for (int i = 0; i <=m/2; i++)
		{
			if (arr[i] != arr[m - 1 - i])
			return false;
		}
		return true;
}
bool judge2(int a)
{
	for (int i = 2; i*i<=a; i++)
	{
		if (a % i == 0)
			return false;
}
	return true;
}
bool judge3(int a)
{
	if (a == 11)
		return true;
	if ((a >= 10 && a <= 100) || (a >= 1000 && a <= 9999) || (a >= 100000 && a <= 999999) || (a >= 10000000 && a <= 99999999))
	{
		return false;
	}
	return true;
	
}
int main()
{
	int a, b;
	cin >> a >> b;
	if (a % 2 == 0)
		a++;
	for (int i = a; i <= b; i+=2)
	{
			if (judge1(i) & judge2(i)&judge3(i))
			{
				printf("%d\n", i);
			}
		
	}
	return 0;
}