对于样例的解释：

    初始 a = 3, b = 8, a < b, b -= a, a = 3, b = 5

            a = 3, b = 5, a < b, b -= a, a = 3, b = 2

            a = 3, b = 2, b < a, a -= b, a = 1, b = 2  

            a = 1, b = 2, b > a, b -= a, a = 1, b = 1

因此 1 和 2 总共操作的次数为 4 次  

1 <= a , b<= 10¹⁸