#include <stdio.h>
int judgesu(int x)
{
    for (int i = 2; i * i <= x; i++)
        if (x % i == 0) return 0;
    return 1;
}
int judgehuiwen(int x)
{
    int num = 0;
    int arr[10];
    if (x < 10)
        return 1;
    else {
        while (x!= 0) {
            arr[num] = x % 10;
            x /= 10;
            num++;
        }
        for (int i = 0; i < num/2; i++)
        {
            if (arr[i] != arr[num - 1 - i]) return 0;
        }
        return 1;
    }
}
int main()
{
    int a, b;
    scanf("%d%d", &a, &b);
    for (int i = a; i <= b; i++)
    {
        if (i % 2 != 0)
            if (judgesu(i))
                if (judgehuiwen(i))
                    printf("%d\n", i);
    }
    return 0;
}