Language: C++

#include<algorithm>
#include<cmath>
#include<iomanip>
#include<iostream>
#include<map>
#include<numeric>
#include<queue>
#include<set>
#include<sstream>
#include<unordered_map>
#include<unordered_set>
#include<vector>
using uint = unsigned int;
using ll = long long;
enum : int { M = (int)1e9 + 7 };
enum : ll { MLL = (ll)1e18L + 9 };
#ifdef LOCAL
#include"rprint2.hpp"
#else
#define FUNC(name) template <ostream& out = cout, class... T> void name(T&&...){ }
FUNC(prints) FUNC(printe) FUNC(printw) FUNC(printew) FUNC(printb) FUNC(printd);
#endif
using namespace std;

int main(){
    cin.tie(0);
    ios::sync_with_stdio(false);
    int n, m;
    cin >> n >> m;
    cout << (n - 1) * (m - 1) << '\n';
    return 0;
}


Compiler output:
a.cc:20:30: error: 'ostream' has not been declared
   20 | #define FUNC(name) template <ostream& out = cout, class... T> void name(T&&...){ }
      |                              ^~~~~~~
a.cc:21:1: note: in expansion of macro 'FUNC'
   21 | FUNC(prints) FUNC(printe) FUNC(printw) FUNC(printew) FUNC(printb) FUNC(printd);
      | ^~~~
a.cc:20:45: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
   20 | #define FUNC(name) template <ostream& out = cout, class... T> void name(T&&...){ }
      |                                             ^~~~
a.cc:21:1: note: in expansion of macro 'FUNC'
   21 | FUNC(prints) FUNC(printe) FUNC(printw) FUNC(printew) FUNC(printb) FUNC(printd);
      | ^~~~
In file included from a.cc:4:
/usr/include/c++/14/iostream:63:18: note: 'std::cout' declared here
   63 |   extern ostream cout;          ///< Linked to standard output
      |                  ^~~~
a.cc:20:30: error: 'ostream' has not been declared
   20 | #define FUNC(name) template <ostream& out = cout, class... T> void name(T&&...){ }
      |                              ^~~~~~~
a.cc:21:14: note: in expansion of macro 'FUNC'
   21 | FUNC(prints) FUNC(printe) FUNC(printw) FUNC(printew) FUNC(printb) FUNC(printd);
      |              ^~~~
a.cc:20:45: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
   20 | #define FUNC(name) template <ostream& out = cout, class... T> void name(T&&...){ }
      |                                             ^~~~
a.cc:21:14: note: in expansion of macro 'FUNC'
   21 | FUNC(prints) FUNC(printe) FUNC(printw) FUNC(printew) FUNC(printb) FUNC(printd);
      |              ^~~~
/usr/include/c++/14/iostream:63:18: note: 'std::cout' declared here
   63 |   extern ostream cout;          ///< Linked to standard output
      |                  ^~~~
a.cc:20:30: error: 'ostream' has not been declared
   20 | #define FUNC(name) template <ostream& out = cout, class... T> void name(T&&...){ }
      |                              ^~~~~~~
a.cc:21:27: note: in expansion of macro 'FUNC'
   21 | FUNC(prints) FUNC(printe) FUNC(printw) FUNC(printew) FUNC(printb) FUNC(printd);
      |                           ^~~~
a.cc:20:45: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
   20 | #define FUNC(name) template <ostream& out = cout, class... T> void name(T&&...){ }
      |                                             ^~~~
a.cc:21:27: note: in expansion of macro 'FUNC'
   21 | FUNC(prints) FUNC(printe) FUNC(printw) FUNC(printew) FUNC(printb) FUNC(printd);
      |                           ^~~~
/usr/include/c++/14/iostream:63:18: note: 'std::cout' declared here
   63 |   extern ostream cout;          ///< Linked to standard output
      |                  ^~~~
a.cc:20:30: error: 'ostream' has not been declared
   20 | #define FUNC(name) template <ostream& out = cout, class... T> void name(T&&...){ }
      |                              ^~~~~~~
a.cc:21:40: note: in expansion of macro 'FUNC'
   21 | FUNC(prints) FUNC(printe) FUNC(printw) FUNC(printew) FUNC(printb) FUNC(printd);
      |                                        ^~~~
a.cc:20:45: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
   20 | #define FUNC(name) template <ostream& out = cout, class... T> void name(T&&...){ }
      |                                             ^~~~
a.cc:21:40: note: in expansion of macro 'FUNC'
   21 | FUNC(prints) FUNC(printe) FUNC(printw) FUNC(printew) FUNC(printb) FUNC(printd);
      |                                        ^~~~
/usr/include/c++/14/iostream:63:18: note: 'std::cout' declared here
   63 |   extern ostream cout;          ///< Linked to standard output
      |                  ^~~~
a.cc:20:30: error: 'ostream' has not been declared
   20 | #define FUNC(name) template <ostream& out = cout, class... T> void name(T&&...){ }
      |                              ^~~~~~~
a.cc:21:54: note: in expansion of macro 'FUNC'
   21 | FUNC(prints) FUNC(printe) FUNC(printw) FUNC(printew) FUNC(printb) FUNC(printd);
      |                                                      ^~~~
a.cc:20:45: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
   20 | #define FUNC(name) template <ostream& out = cout, class... T> void name(T&&...){ }
      |                                             ^~~~
a.cc:21:54: note: in expansion of macro 'FUNC'
   21 | FUNC(prints) FUNC(printe) FUNC(printw) FUNC(printew) FUNC(printb) FUNC(printd);
      |                                                      ^~~~
/usr/include/c++/14/iostream:63:18: note: 'std::cout' declared here
   63 |   extern ostream cout;          ///< Linked to standard output
      |                  ^~~~
a.cc:20:30: error: 'ostream' has not been declared
   20 | #define FUNC(name) template <ostream& out = cout, class... T> void name(T&&...){ }
      |                              ^~~~~~~
a.cc:21:67: note: in expansion of macro 'FUNC'
   21 | FUNC(prints) FUNC(printe) FUNC(printw) FUNC(printew) FUNC(printb) FUNC(printd);
      |                                                                   ^~~~
a.cc:20:45: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
   20 | #define FUNC(name) template <ostream& out = cout, class... T> void name(T&&...){ }
      |                                             ^~~~
a.cc:21:67: note: in expansion of macro 'FUNC'
   21 | FUNC(prints) FUNC(printe) FUNC(printw) FUNC(printew) FUNC(printb) FUNC(printd);
      |                                                                   ^~~~
/usr/include/c++/14/iostream:63:18: note: 'std::cout' declared here
   63 |   extern ostream cout;          ///< Linked to standard output
      |                  ^~~~