#include<iostream>
#include<cstring>
using namespace std;
bool zs[100000001];
void ZS(int b)
{
	memset(zs, true, sizeof(zs));
	{
		zs[1] = false;
		for (int i = 2; i * i <= b; i++)
		{
			if (zs[i])
			{
				for (int m = 2; m * i <= b; m++)
				{
					zs[i * m] = false;
				}
			}
		}
	}
}
bool HWS(int n)
{
	int temp = n;
	int m = 0;
	while (temp != 0)
	{
		m = m * 10 + temp %10;
		temp/= 10;
	}
	if (m == n)
		return true;
	else return false;
}
int main()
{
	int a, b;
	cin >> a >> b;
	int i = a;
	ZS(b);
	if (i % 2 == 0)i++;
	if (a > b)return 0;
	if (b > 100000000)
	{
		b = 99999999;
	}
	for (i; i <= b; i++)
	{
		if (zs[i] && HWS(i))
		{
			cout << i << endl;
		}

	}
}