#include <cstdio>

inline bool is_prime(int n)
{
    for (int i = 2; i * i <= n; i++)
        if (n % i == 0)
            return false;
    return true;
}

int main()
{
    int a, b;
    scanf("%d%d", &a, &b);

    for (int i = 0; i <= 9; i++)
        for (int j = 0; j <= 9; j++)
            for (int k = 0; k <= 9; k++)
                for (int m = 0; m <= 9; m++)
                {
                    int n = i * 1000 + j * 100 + k * 10 + m;
                    n = n * 1000 + k * 100 + j * 10 + i;
                    while (n % 10 == 0 && n)
                        n /= 10;
                    if (n < a)
                        continue;
                    if (n > b)
                        return 0;
                    if (is_prime(n))
                        printf("%d\n", n);
                }

    return 0;
}