Language: C++

#include <bits/stdc++.h>
int main(){
    string a;
    cin>>a;
   int len =a.size();
   if(len==2)cout<<a<<endl;
  else cout<<reverse(a.begin(),a.end());<<endl;
     return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:3:5: error: 'string' was not declared in this scope
    3 |     string a;
      |     ^~~~~~
a.cc:3:5: note: suggested alternatives:
In file included from /usr/include/c++/14/string:41,
                 from /usr/include/c++/14/bitset:52,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:52,
                 from a.cc:1:
/usr/include/c++/14/bits/stringfwd.h:77:33: note:   'std::string'
   77 |   typedef basic_string<char>    string;
      |                                 ^~~~~~
/usr/include/c++/14/string:76:11: note:   'std::pmr::string'
   76 |     using string    = basic_string<char>;
      |           ^~~~~~
a.cc:4:5: error: 'cin' was not declared in this scope; did you mean 'std::cin'?
    4 |     cin>>a;
      |     ^~~
      |     std::cin
In file included from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:146:
/usr/include/c++/14/iostream:62:18: note: 'std::cin' declared here
   62 |   extern istream cin;           ///< Linked to standard input
      |                  ^~~
a.cc:4:10: error: 'a' was not declared in this scope
    4 |     cin>>a;
      |          ^
a.cc:6:14: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
    6 |    if(len==2)cout<<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:6:23: error: 'endl' was not declared in this scope; did you mean 'std::endl'?
    6 |    if(len==2)cout<<a<<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:7:8: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
    7 |   else cout<<reverse(a.begin(),a.end());<<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:7:14: error: 'reverse' was not declared in this scope; did you mean 'std::reverse'?
    7 |   else cout<<reverse(a.begin(),a.end());<<endl;
      |              ^~~~~~~
      |              std::reverse
In file included from /usr/include/c++/14/algorithm:86,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:51:
/usr/include/c++/14/pstl/glue_algorithm_defs.h:249:1: note: 'std::reverse' declared here
  249 | reverse(_ExecutionPolicy&& __exec, _BidirectionalIterator __first, _BidirectionalIterator __last);
      | ^~~~~~~
a.cc:7:41: error: expected primary-expression before '<<' token
    7 |   else cout<<reverse(a.begin(),a.end());<<endl;
      |                                         ^~
a.cc:7:43: error: 'endl' was not declared in this scope; did you mean 'std::endl'?
    7 |   else cout<<reverse(a.begin(),a.end());<<endl;
      |                                           ^~~~
      |                                           std::endl
/usr/include/c++/14/ostream:744:5: note: 'std::endl' declared here
  744 |     endl(basic_ostream<_CharT, _Traits>& __os)
      |     ^~~~