头文件 — 备忘

/*
                                             __----~~~~~~~~~~~------___
                                  .  .   ~~//====......          __--~ ~~
                  -.            \_|//     |||\  ~~~~~~::::... /~
               ___-==_       _-~o~  /    |||  \            _/~~-
       __---~~~.==~||=_    -_--~/_-~|-   |\   \        _/~
   _-~~     .=~    |  \-_    '-~7  /-   /  ||          /
 .~       .~       |   \ -_    /  /-   /   ||         /
/  ____  /         |     \ ~-_/  /|- _/   .||        /
|~~    ~~|--~~~~--_      ~==-/   | ~--===~~        .
         '         ~-|      /|    |-~~~       __--~~
                     |-~~-_/ |    |   ~\_   _-~            /
                          /       \__   /~                \__
                      _--~ _/ | .-~~____--~-/                  ~~==.
                     ((->/~   '.|||' -_|    ~~-/ ,              . _||
                                -_     ~      ~~---l__i__i__i--~~_/
                                _-~-__   ~)  --______________--~~
                              //.-~~~-~_--~- |-------~~~~~~~~
                                     //.-~~~--
*/
#define _CRT_SECURE_NO_WARNINGS
#include<cstdio>
#include<iostream>
#include<cstring>
#include<algorithm>
#include<bitset>
#include<cassert>
#include<cctype>
#include<cmath>
#include<cstdlib>
#include<ctime>
#include<deque>
#include<iomanip>
#include<list>
#include<map>
#include<queue>
#include<set>
#include<stack>
#include<vector>
#define lt k << 1
#define rt k << 1 | 1
#define lowbit(x) x & (-x)
#define lson l, mid, lt
#define rson mid+1, r, rt
using namespace std;
typedef long long ll;
typedef long double ld;
#define fin freopen("in.txt", "r", stdin);
#define fout freopen("out.txt", "w", stdout);
#define ios ios::sync_with_stdio(false); cin.tie(0); cout.tie(0);
#define mem(a, b) memset(a, b, sizeof(a))
//#define int ll
const double pi = acos(-1.0);
const double eps = 1e-8;
const ll mod = 1e9 + 7;
const int inf = 0x3f3f3f3f;
const ll INF = 0x3f3f3f3f3f3f3f3f;
const int maxn = 2e5 + 500;