#include <iostream>
#include <string>
#include <vector>
#include <cmath>
using namespace std;
bool hw(string a)
{

    int len = a.length();
    bool zt = true;
    for (int i = len / 2 - 1; i >= 0; i--)
    {
        if (a[len - i - 1] != a[i])
        {
            zt = false;
            break;
        }
    }
    return zt;
}

bool zs(int a)
{
    for (int i = 2; i <= sqrt(a); i++)
    {
        if (a % i == 0)
        {
            return false;
        }
    }
    return true;
}

vector<int> shz;

int main()
{
    shz.push_back(0);
    int a, b;
    cin >> a >> b;
    for (int i = a; i <= b; i++)
    {
        if (hw(to_string(i)))
        {
            shz.push_back(i);
        }
    }
    for (int i = 1; i < shz.size(); i++)
    {
        if (zs(shz[i]))
        {
            printf("%d\n", shz[i]);
        }
    }
    return 0;
}