Language: C++

#include<iostream>
#include<algorithm>

int a, b, c;

void ans(void);

int main(void){
cin >>a >>b >>c;
cout <<a b c;

return 0;
}

void ans(void){
if(a > b){
swap(a, b);
}
if(b > c){
swap(b, c);
}
if(a > b){
swap(a, b);
}
}

Compiler output:
a.cc: In function 'int main()':
a.cc:9:1: error: 'cin' was not declared in this scope; did you mean 'std::cin'?
    9 | 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:10:1: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
   10 | cout <<a b c;
      | ^~~~
      | std::cout
/usr/include/c++/14/iostream:63:18: note: 'std::cout' declared here
   63 |   extern ostream cout;          ///< Linked to standard output
      |                  ^~~~
a.cc: In function 'void ans()':
a.cc:17:1: error: 'swap' was not declared in this scope
   17 | swap(a, b);
      | ^~~~
a.cc:17:1: note: suggested alternatives:
In file included from /usr/include/c++/14/bits/memory_resource.h:47,
                 from /usr/include/c++/14/string:68,
                 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,
                 from /usr/include/c++/14/ostream:40,
                 from /usr/include/c++/14/iostream:41:
/usr/include/c++/14/tuple:2823:5: note:   'std::swap'
 2823 |     swap(tuple<_Elements...>&, tuple<_Elements...>&) = delete;
      |     ^~~~
In file included from /usr/include/c++/14/bits/exception_ptr.h:41,
                 from /usr/include/c++/14/exception:166,
                 from /usr/include/c++/14/ios:41:
/usr/include/c++/14/bits/move.h:226:5: note:   'std::swap'
  226 |     swap(_Tp& __a, _Tp& __b)
      |     ^~~~
/usr/include/c++/14/bits/move.h:226:5: note:   'std::swap'
/usr/include/c++/14/bits/exception_ptr.h:229:5: note:   'std::__exception_ptr::swap'
  229 |     swap(exception_ptr& __lhs, exception_ptr& __rhs)
      |     ^~~~
a.cc:20:1: error: 'swap' was not declared in this scope
   20 | swap(b, c);
      | ^~~~
a.cc:20:1: note: suggested alternatives:
/usr/include/c++/14/tuple:2823:5: note:   'std::swap'
 2823 |     swap(tuple<_Elements...>&, tuple<_Elements...>&) = delete;
      |     ^~~~
/usr/include/c++/14/bits/move.h:226:5: note:   'std::swap'
  226 |     swap(_Tp& __a, _Tp& __b)
      |     ^~~~
/usr/include/c++/14/bits/move.h:226:5: note:   'std::swap'
/usr/include/c++/14/bits/exception_ptr.h:229:5: note:   'std::__exception_ptr::swap'
  229 |     swap(exception_ptr& __lhs, exception_ptr& __rhs)
      |     ^~~~
a.cc:23:1: error: 'swap' was not declared in this scope
   23 | swap(a, b);
      | ^~~~
a.cc:23:1: note: suggested alternatives:
/usr/include/c++/14/tuple:2823:5: note:   'std::swap'
 2823 |     swap(tuple<_Elements...>&, tuple<_Elements...>&) = delete;
      |     ^~~~
/usr/include/c++/14/bits/move.h:226:5: note:   'std::swap'
  226 |     swap(_Tp& __a, _Tp& __b)
      |     ^~~~
/usr/include/c++/14/bits/move.h:226:5: note:   'std::swap'
/usr/include/c++/14/bits/exception_ptr.h:229:5: note:   'std::__exception_ptr::swap'
  229 |     swap(exception_ptr& __lhs, exception_ptr& __rhs)
      |     ^~~~