#include<iostream>
#include<vector>
using namespace std;
bool ip(int n) {
	if (n <= 3) return n > 1;
	for (int d = 2; d * d <= n; ++d)
		if (n % d == 0) return 0;
	return 1;
}
bool hw(int b)
{
	vector<int>arr;
	while (b > 0)
	{
		
		int temp = b;
		arr.push_back ( temp % 10);
		b /= 10;
	}
	int ans = arr.size();
	for (int i = 0; i < ans/2; i++)
	{
		if (arr[i] != arr[ans - i - 1])
			return false;
	}
	return true;
}
int main()
{
	int a, b;
	cin >> a >> b;
	for (int i = a; i <= b; i++)
	{
		bool n = (ip(i) && hw(i));
		if (n)cout << i << endl;
	}

return 0;
}