#include<iostream>
using namespace std;
#include<stdio.h>
#include<cmath>
#include<cstring>
bool su(int x)
{
    if (x == 2 || x == 3)
    {
        return true;
    }
    for (int i = 2; i <= (int)sqrt(x); i += 2)
    {
        if (x % i == 0)
        {
            return false;
        }
        i--;
    }
    return true;
}

bool hui(char s[])
{
    for (int i = 0; i <=(int)strlen(s)/2; i++)
    {
        if (s[i] == s[strlen(s) - i - 1])
        {

        }
        else
        {
            return false;
        }
    }
    return true;
}
int main()
{
    char x[13];
    int a, b;
    cin >> a >> b;
    for (int i = a; i <= b; i++)
    {
        sprintf(x, "%d", i);
        //s = x;
        if (hui(x))
        {
            if (su(i))
            {
                printf("%d\n",i);
            }
        }
        else
        {

        }
    }

}