n = 31
num = n
answer = 0

while True:
    answer = 0

    if num >= n:
        answer += 1

    reversed = int(str(num)[::-1])
    if num == reversed:
        answer += 1

    is_prime = True
    if num < 2:
        is_prime = False
    else:
        for i in range(2, int(num ** 0.5) + 1):
            if num % i == 0:
                is_prime = False
                break

    if is_prime:
        answer += 1

    if answer >= 3:
        print(num)
        break

    num += 1