Language: C++

#include <iostream>

int main(){
			int a,b;

			cin >> a >> b;
			if(a < b)cout << "a < b" << endl;
			else if(a > b)cout << "a > b" << endl;
			else cout << "a == b" << endl;

	return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:6:25: error: 'cin' was not declared in this scope; did you mean 'std::cin'?
    6 |                         cin >> a >> b;
      |                         ^~~
      |                         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:7:34: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
    7 |                         if(a < b)cout << "a < b" << 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:7:53: error: 'endl' was not declared in this scope; did you mean 'std::endl'?
    7 |                         if(a < b)cout << "a < b" << 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:8:39: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
    8 |                         else if(a > b)cout << "a > b" << 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:8:58: error: 'endl' was not declared in this scope; did you mean 'std::endl'?
    8 |                         else if(a > b)cout << "a > b" << endl;
      |                                                          ^~~~
      |                                                          std::endl
/usr/include/c++/14/ostream:744:5: note: 'std::endl' declared here
  744 |     endl(basic_ostream<_CharT, _Traits>& __os)
      |     ^~~~
a.cc:9:30: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
    9 |                         else cout << "a == b" << 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:9:50: error: 'endl' was not declared in this scope; did you mean 'std::endl'?
    9 |                         else cout << "a == b" << endl;
      |                                                  ^~~~
      |                                                  std::endl
/usr/include/c++/14/ostream:744:5: note: 'std::endl' declared here
  744 |     endl(basic_ostream<_CharT, _Traits>& __os)
      |     ^~~~