Language: C++

#include<bits/stdc++.h>
using nmespace std;
int main()
{
  char a,b;
  cin >> a >> b;
  if(a=='H' && b=='H')
    cout << "H" << endl;
  else if(a=='D' && b=='H')
    cout << "D" << endl;
  else if(a=='H' && b=='D')
    cout << "D" << endl;
  else if(a=='D' && b=='D')
    cout << "H" << endl;
}

Compiler output:
a.cc:2:7: error: expected nested-name-specifier before 'nmespace'
    2 | using nmespace std;
      |       ^~~~~~~~
a.cc: In function 'int main()':
a.cc:6:3: error: 'cin' was not declared in this scope; did you mean 'std::cin'?
    6 |   cin >> a >> b;
      |   ^~~
      |   std::cin
In file included from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:146,
                 from a.cc:1:
/usr/include/c++/14/iostream:62:18: note: 'std::cin' declared here
   62 |   extern istream cin;           ///< Linked to standard input
      |                  ^~~
a.cc:8:5: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
    8 |     cout << "H" << endl;
      |     ^~~~
      |     std::cout
/usr/include/c++/14/iostream:63:18: note: 'std::cout' declared here
   63 |   extern ostream cout;          ///< Linked to standard output
      |                  ^~~~
a.cc:8:20: error: 'endl' was not declared in this scope; did you mean 'std::endl'?
    8 |     cout << "H" << endl;
      |                    ^~~~
      |                    std::endl
In file included from /usr/include/c++/14/istream:41,
                 from /usr/include/c++/14/sstream:40,
                 from /usr/include/c++/14/complex:45,
                 from /usr/include/c++/14/ccomplex:39,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:127:
/usr/include/c++/14/ostream:744:5: note: 'std::endl' declared here
  744 |     endl(basic_ostream<_CharT, _Traits>& __os)
      |     ^~~~
a.cc:10:5: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
   10 |     cout << "D" << endl;
      |     ^~~~
      |     std::cout
/usr/include/c++/14/iostream:63:18: note: 'std::cout' declared here
   63 |   extern ostream cout;          ///< Linked to standard output
      |                  ^~~~
a.cc:10:20: error: 'endl' was not declared in this scope; did you mean 'std::endl'?
   10 |     cout << "D" << endl;
      |                    ^~~~
      |                    std::endl
/usr/include/c++/14/ostream:744:5: note: 'std::endl' declared here
  744 |     endl(basic_ostream<_CharT, _Traits>& __os)
      |     ^~~~
a.cc:12:5: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
   12 |     cout << "D" << endl;
      |     ^~~~
      |     std::cout
/usr/include/c++/14/iostream:63:18: note: 'std::cout' declared here
   63 |   extern ostream cout;          ///< Linked to standard output
      |                  ^~~~
a.cc:12:20: error: 'endl' was not declared in this scope; did you mean 'std::endl'?
   12 |     cout << "D" << endl;
      |                    ^~~~
      |                    std::endl
/usr/include/c++/14/ostream:744:5: note: 'std::endl' declared here
  744 |     endl(basic_ostream<_CharT, _Traits>& __os)
      |     ^~~~
a.cc:14:5: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
   14 |     cout << "H" << endl;
      |     ^~~~
      |     std::cout
/usr/include/c++/14/iostream:63:18: note: 'std::cout' declared here
   63 |   extern ostream cout;          ///< Linked to standard output
      |                  ^~~~
a.cc:14:20: error: 'endl' was not declared in this scope; did you mean 'std::endl'?
   14 |     cout << "H" << endl;
      |                    ^~~~
      |                    std::endl
/usr/include/c++/14/ostream:744:5: note: 'std::endl' declared here
  744 |     endl(basic_ostream<_CharT, _Traits>& __os)
      |     ^~~~