盗用名字：C题题目都没看懂，
B:You are given a long long n. Return the largest divisor of n that is a perfect square. That is, the correct return value is x if and only if:
- x divides n
- There is an integer y such that x = y*y.
- x is the largest integer that satisfies conditions 1 and 2.
题目就是求最大的X*X 使N MOD (X*X)=0;
N <=10^18;
我的做法不同于很多人；
假如X*X*Y=N;
1:先枚举Y的情况枚举1-1234567左右去寻找X*X是否存在；
2:然后枚举X判断Y存在是X*X的最大值。
通过两段枚举能找到最大值