模板
//头文件+预处理
#include<iostream>
#include<cstdlib>
#include<cstdio>
#include<cstring>
#include<string>
#include<vector>
#include<map>
#include<set>
#include<queue>
#include<stack>
#define ll long long
#define myfor(c,a,b) for(int c=a;a<=b?c<=b:c>=b;a<=b?++c:--c)
#define sfor(a,b,c) for(int a=b;a<=c;++a)
#define nfor(a,b,c) for(int a=b;a>=c;--a)
const ll maxn=10005;