int ZS(int a)
{
	for (int i = 2; i <= sqrt(a); i++)
		if (a % i == 0)return 0;
	return 1;
}
int HW(int a)
{
	stringstream s;
	s << a;
	string temp = s.str();
	for (int i = 0, j = temp.size() - 1; i<j; i++, j--)
	{
		if (temp[i] != temp[j])return 0;
	}
	s.str("");
	s.clear();
	return 1;
}
int main()
{
	int x, y;
	cin >> x >> y;
	for (int i = x; i <= y;)
	{
		if (HW(i))
		{
			if (ZS(i))
				cout << i << endl;
		}
		if (i == x && x % 2 == 0)
		{
			i++; continue;
		}
		i += 2;
	}
	return 0;
}