NUM_PRIMES = 11
START_NUM = 9


def is_prime(n):
    """Returns True if n is prime."""
    if n == 1:
        return False
    if n == 2:
        return True
    if n == 3:
        return True
    if n % 2 == 0:
        return False
    if n % 3 == 0:
        return False

    i = 5
    w = 2

    while i * i <= n:
        if n % i == 0:
            return False
        i += w
        w = 6 - w

    return True


def truncatable_prime(i):
    j = i
    for _ in range(len(j)):
        if not is_prime(int(j)):
            return False
        j = j[1:]
    j = i
    for _ in range(len(j)):
        if not is_prime(int(j)):
            return False
        j = j[:-1]
    return True


if __name__ == '__main__':
    results = []
    i = START_NUM
    while len(results) != NUM_PRIMES:
        i += 1
        if truncatable_prime(str(i)):
            results.append(i)

    print(results)
    print(sum(results))