def is_prime(n):
    """判断是否为质数"""
    if n < 2:
        return False
    if n in (2, 3):
        return True
    if n % 2 == 0:
        return False
    # 只需检查到sqrt(n)即可
    for i in range(3, int(n**0.5)+1, 2):
        if n % i == 0:
            return False
    return True
# 先生成回文数再判断质数
def main():
    a, b = map(int, input().split())
    if 5 <= a <= b <= 10**8 and a < b:
        # 先生成回文数再判断质数
        for num in range(a, b+1):
            if str(num) == str(num)[::-1]:  # 判断回文
                if is_prime(num):  # 判断质数
                    print(num)
if __name__ == '__main__':
    main()