#include<iostream>
#include<cstring>
#include<algorithm>

using namespace std;

const int N = 1e8+10;
int a, b;
int primes[N];	//质数的数组！ 
bool st[N];
int cnt;

void is_prime(int n)
{
	for (int i=2; i <= n; i ++)
	{
		if (!st[i]) primes[cnt ++] = i;
		for (int j=0; primes[j]*i <= n; j ++)
		{
			st[primes[j]*i] = true;
			if (i % primes[j] == 0) break;
		}
	}
}

bool huiwen (int nums)
{
	string str = to_string(nums);
	int l=0, r=str.size()-1;
	while (l < r)
	{
		if (str[l++] != str[r--])
			return false;
	}

	return true;
}

int main()
{
	cin >> a >> b;
	is_prime(b);	

	for (int i=0; i < cnt; i ++)
	{
		if (primes[i] >= a && primes[i] <= b)
			if (huiwen(primes[i]))
				cout << primes[i] << endl;
	}
	return 0;
}