#include<bits/stdc++.h>
#define int long long
using namespace std;
signed main(){
  freopen("test.in","r",stdin);
  freopen("test.out","w",stdout);
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  //....
  return 0;
}

关于 #define int long long：知道要检查空间。