Language: C++

#include<iostream>
//白日依山尽
#define usn using namespace
#define it int main()
//黄河入海流
#define ci(i,n) cin>>i>>n
#define co(ans) cout<<ans<<endl
#define st string
//欲穷千里目
usn;
it
{st i,n;
 ci(i,n);
 if(i=="H")
{co(n);
}
 else
{if(n=="H")
 co("D");
 else
 co("H");
}
return 0;
}


Compiler output:
a.cc:10:4: error: expected identifier before ';' token
   10 | usn;
      |    ^
a.cc: In function 'int main()':
a.cc:8:12: error: 'string' was not declared in this scope
    8 | #define st string
      |            ^~~~~~
a.cc:12:2: note: in expansion of macro 'st'
   12 | {st i,n;
      |  ^~
a.cc:8:12: note: suggested alternatives:
    8 | #define st string
      |            ^~~~~~
a.cc:12:2: note: in expansion of macro 'st'
   12 | {st i,n;
      |  ^~
In file included from /usr/include/c++/14/iosfwd:41,
                 from /usr/include/c++/14/ios:40,
                 from /usr/include/c++/14/ostream:40,
                 from /usr/include/c++/14/iostream:41,
                 from a.cc:1:
/usr/include/c++/14/bits/stringfwd.h:77:33: note:   'std::string'
   77 |   typedef basic_string<char>    string;
      |                                 ^~~~~~
In file included from /usr/include/c++/14/bits/locale_classes.h:40,
                 from /usr/include/c++/14/bits/ios_base.h:41,
                 from /usr/include/c++/14/ios:44:
/usr/include/c++/14/string:76:11: note:   'std::pmr::string'
   76 |     using string    = basic_string<char>;
      |           ^~~~~~
a.cc:6:17: error: 'cin' was not declared in this scope; did you mean 'std::cin'?
    6 | #define ci(i,n) cin>>i>>n
      |                 ^~~
a.cc:13:2: note: in expansion of macro 'ci'
   13 |  ci(i,n);
      |  ^~
/usr/include/c++/14/iostream:62:18: note: 'std::cin' declared here
   62 |   extern istream cin;           ///< Linked to standard input
      |                  ^~~
a.cc:13:5: error: 'i' was not declared in this scope; did you mean 'it'?
   13 |  ci(i,n);
      |     ^
a.cc:6:22: note: in definition of macro 'ci'
    6 | #define ci(i,n) cin>>i>>n
      |                      ^
a.cc:13:7: error: 'n' was not declared in this scope
   13 |  ci(i,n);
      |       ^
a.cc:6:25: note: in definition of macro 'ci'
    6 | #define ci(i,n) cin>>i>>n
      |                         ^
a.cc:7:17: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
    7 | #define co(ans) cout<<ans<<endl
      |                 ^~~~
a.cc:15:2: note: in expansion of macro 'co'
   15 | {co(n);
      |  ^~
/usr/include/c++/14/iostream:63:18: note: 'std::cout' declared here
   63 |   extern ostream cout;          ///< Linked to standard output
      |                  ^~~~
a.cc:7:28: error: 'endl' was not declared in this scope; did you mean 'std::endl'?
    7 | #define co(ans) cout<<ans<<endl
      |                            ^~~~
a.cc:15:2: note: in expansion of macro 'co'
   15 | {co(n);
      |  ^~
/usr/include/c++/14/ostream:744:5: note: 'std::endl' declared here
  744 |     endl(basic_ostream<_CharT, _Traits>& __os)
      |     ^~~~
a.cc:7:17: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
    7 | #define co(ans) cout<<ans<<endl
      |                 ^~~~
a.cc:19:2: note: in expansion of macro 'co'
   19 |  co("D");
      |  ^~
/usr/include/c++/14/iostream:63:18: note: 'std::cout' declared here
   63 |   extern ostream cout;          ///< Linked to standard output
      |                  ^~~~
a.cc:7:28: error: 'endl' was not declared in this scope; did you mean 'std::endl'?
    7 | #define co(ans) cout<<ans<<endl
      |                            ^~~~
a.cc:19:2: note: in expansion of macro 'co'
   19 |  co("D");
      |  ^~
/usr/include/c++/14/ostream:744:5: note: 'std::endl' declared here
  744 |     endl(basic_ostream<_CharT, _Traits>& __os)
      |     ^~~~
a.cc:7:17: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
    7 | #define co(ans) cout<<ans<<endl
      |                 ^~~~
a.cc:21:2: note: in expansion of macro 'co'
   21 |  co("H");
      |  ^~
/usr/include/c++/14/iostream:63:18: note: 'std::cout' declared here
   63 |   extern ostream cout;          ///< Linked to standard output
      |                  ^~~~
a.cc:7:28: error: 'endl' was not declared in this scope; did you mean 'std::endl'?
    7 | #define co(ans) cout<<ans<<endl
      |                            ^~~~
a.cc:21:2: note: in expansion of macro 'co'
   21 |  co("H");
      |  ^~
/usr/include/c++/14/ostream:744:5: note: 'std::endl' declared here
  744 |     endl(basic_ostream<_CharT, _Traits>& __os)
      |     ^~~~