Language: C++

#include <iostream>
using  namespace???std;

int main() {
  int a,b,c;
  cin >> a >> b >> c;
  if ( a < b) {
    if ( b < c) {
      cout << a << " " << b << " " << c << endl;
    }
  }else if( a > b) {
    if ( a < c) {
      cout << b << " " << a << " " << c << endl;  
    }else if ( a > c) {
      cout << c << " " << b << " " << a << endl;
    }
  }
}

Compiler output:
a.cc:2:17: error: expected identifier before '?' token
    2 | using  namespace???std;
      |                 ^
a.cc:2:17: error: expected ';' before '?' token
    2 | using  namespace???std;
      |                 ^
      |                 ;
a.cc:2:17: error: expected unqualified-id before '?' token
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 >> c;
      |   ^~~
      |   std::cin
In file included 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:9:7: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
    9 |       cout << a << " " << b << " " << c << 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:9:44: error: 'endl' was not declared in this scope; did you mean 'std::endl'?
    9 |       cout << a << " " << b << " " << c << endl;
      |                                            ^~~~
      |                                            std::endl
In file included from /usr/include/c++/14/iostream:41:
/usr/include/c++/14/ostream:744:5: note: 'std::endl' declared here
  744 |     endl(basic_ostream<_CharT, _Traits>& __os)
      |     ^~~~
a.cc:13:7: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
   13 |       cout << b << " " << a << " " << c << 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:13:44: error: 'endl' was not declared in this scope; did you mean 'std::endl'?
   13 |       cout << b << " " << a << " " << c << endl;
      |                                            ^~~~
      |                                            std::endl
/usr/include/c++/14/ostream:744:5: note: 'std::endl' declared here
  744 |     endl(basic_ostream<_CharT, _Traits>& __os)
      |     ^~~~
a.cc:15:7: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
   15 |       cout << c << " " << b << " " << a << 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:15:44: error: 'endl' was not declared in this scope; did you mean 'std::endl'?
   15 |       cout << c << " " << b << " " << a << endl;
      |                                            ^~~~
      |                                            std::endl
/usr/include/c++/14/ostream:744:5: note: 'std::endl' declared here
  744 |     endl(basic_ostream<_CharT, _Traits>& __os)
      |     ^~~~