Language: C++

#include<bits/stdc++.h>

#define FOR(i,a,b) for(int i=(a);i<(int)(b);++i)
#define REP(i,n) FOR(i,0,n)


int main(){
    std::ios::sync_with_stdio(false);
    std::cin.tie(0);

    int num;
    string str;
    cin >> num >> str;
    if(num>=3500){
        cout << str << endl;
    }else{
        cout << "red" << endl;
    }   
}


Compiler output:
a.cc: In function 'int main()':
a.cc:12:5: error: 'string' was not declared in this scope
   12 |     string str;
      |     ^~~~~~
a.cc:12:5: 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:13:5: error: 'cin' was not declared in this scope; did you mean 'std::cin'?
   13 |     cin >> num >> str;
      |     ^~~
      |     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:13:19: error: 'str' was not declared in this scope; did you mean 'std'?
   13 |     cin >> num >> str;
      |                   ^~~
      |                   std
a.cc:15:9: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
   15 |         cout << str << 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:15:24: error: 'endl' was not declared in this scope; did you mean 'std::endl'?
   15 |         cout << str << 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:17:9: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
   17 |         cout << "red" << 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:17:26: error: 'endl' was not declared in this scope; did you mean 'std::endl'?
   17 |         cout << "red" << endl;
      |                          ^~~~
      |                          std::endl
/usr/include/c++/14/ostream:744:5: note: 'std::endl' declared here
  744 |     endl(basic_ostream<_CharT, _Traits>& __os)
      |     ^~~~