基本操作

#include<iostream>
#include<iomanip>
#include<cstdio>
#include<algorithm>
#include<cstring>
#include<cmath>
#include<queue>
#include<stack>
#include<vector>
#include<string>
#include<map>
#include<set>
#include<ctime>
#define ll  long long
#define ull unsigned long long
using namespace std;
const int N=2e5+5,MM=10007;
const ull base=13331;
const double Pi=acos(-1.0);
const ll C=299792458;
//读入挂
inline void read(int &x){char ch;bool ok;
for(ok=0,ch=getchar();!isdigit(ch);ch=getchar()) if(ch=='-') ok=1;
for(x=0;isdigit(ch);x=x*10+ch-'0',ch=getchar());if(ok) x=-x;}
namespace IO {
    const int MX = 4e7; //1e7 占用内存 11000kb
    char buf[MX]; int c, sz;
    void Begin() {
        c = 0;
        sz = fread(buf, 1, MX, stdin);//一次性全部读入
    }
    inline bool Read(int &t) {
        while (c < sz && buf[c] != '-' && (buf[c] < '0' || buf[c] > '9')) c++;
        if (c >= sz) return false;//若读完整个缓冲块则退出
        bool flag = 0; if(buf[c] == '-') flag = 1, c++;
        for(t = 0; c < sz && '0' <= buf[c] && buf[c] <= '9'; c++) t = t * 10 + buf[c] - '0';
        if(flag) t = -t;
        return true;
    }
}