Language: C++

#include<bits/stdc++.h>
int main()
{
string a;  
cin >> a;

  
  if(a=="SAT"){
cout << '1' << endl;}
  if(a=="FRI"){
cout << '2' << endl;}
if(a=="THU"){
cout << '3' << endl;}
if(a=="WED"){
cout << '4' << endl;}
if(a=="TUE"){
cout << '5' << endl;}
  if(a=="MON"){
cout << '6' << endl;}
  if(a=="SUN"){
cout << '7' << endl;}
  
  
return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:4:1: error: 'string' was not declared in this scope
    4 | string a;
      | ^~~~~~
a.cc:4:1: 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:5:1: error: 'cin' was not declared in this scope; did you mean 'std::cin'?
    5 | 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:5:8: error: 'a' was not declared in this scope
    5 | cin >> a;
      |        ^
a.cc:9:1: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
    9 | cout << '1' << 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:9:16: error: 'endl' was not declared in this scope; did you mean 'std::endl'?
    9 | cout << '1' << 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:11:1: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
   11 | cout << '2' << 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:11:16: error: 'endl' was not declared in this scope; did you mean 'std::endl'?
   11 | cout << '2' << endl;}
      |                ^~~~
      |                std::endl
/usr/include/c++/14/ostream:744:5: note: 'std::endl' declared here
  744 |     endl(basic_ostream<_CharT, _Traits>& __os)
      |     ^~~~
a.cc:13:1: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
   13 | cout << '3' << 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:13:16: error: 'endl' was not declared in this scope; did you mean 'std::endl'?
   13 | cout << '3' << endl;}
      |                ^~~~
      |                std::endl
/usr/include/c++/14/ostream:744:5: note: 'std::endl' declared here
  744 |     endl(basic_ostream<_CharT, _Traits>& __os)
      |     ^~~~
a.cc:15:1: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
   15 | cout << '4' << 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:15:16: error: 'endl' was not declared in this scope; did you mean 'std::endl'?
   15 | cout << '4' << endl;}
      |                ^~~~
      |                std::endl
/usr/include/c++/14/ostream:744:5: note: 'std::endl' declared here
  744 |     endl(basic_ostream<_CharT, _Traits>& __os)
      |     ^~~~
a.cc:17:1: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
   17 | cout << '5' << 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:17:16: error: 'endl' was not declared in this scope; did you mean 'std::endl'?
   17 | cout << '5' << endl;}
      |                ^~~~
      |                std::endl
/usr/include/c++/14/ostream:744:5: note: 'std::endl' declared here
  744 |     endl(basic_ostream<_CharT, _Traits>& __os)
      |     ^~~~
a.cc:19:1: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
   19 | cout << '6' << 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:19:16: error: 'endl' was not declared in this scope; did you mean 'std::endl'?
   19 | cout << '6' << endl;}
      |                ^~~~
      |                std::endl
/usr/include/c++/14/ostream:744:5: note: 'std::endl' declared here
  744 |     endl(basic_ostream<_CharT, _Traits>& __os)
      |     ^~~~
a.cc:21:1: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
   21 | cout << '7' << 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:21:16: error: 'endl' was not declared in this scope; did you mean 'std::endl'?
   21 | cout << '7' << endl;}
      |                ^~~~
      |                std::endl
/usr/include/c++/14/ostream:744:5: note: 'std::endl' declared here
  744 |     endl(basic_ostream<_CharT, _Traits>& __os)
      |     ^~~~