Language: C++

#include <iostream>
#include <string>
#include <algorithm>
#include <functional>
#include <vector>
#include <stack>
#include <queue>
#include <set>
#include <map>
#include <cstdio>
#include <cmath>
#include <tuple>
#define rep(i, n) for(i = 0; i < n; i++)

signed main() {
	string s;
	cin >> s;
	if (s[0] == s[1] || s[1] == s[2] || s[2] == s[3]) {
		cout << "Bad" << endl;
	}
	else {
		cout << "Good" << endl;
	}
	return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:16:9: error: 'string' was not declared in this scope
   16 |         string s;
      |         ^~~~~~
a.cc:16:9: note: suggested alternatives:
In file included from /usr/include/c++/14/iosfwd:41,
                 from /usr/include/c++/14/ios:40,
                 from /usr/include/c++/14/ostream:40,
                 from /usr/include/c++/14/iostream:41,
                 from a.cc:1:
/usr/include/c++/14/bits/stringfwd.h:77:33: note:   'std::string'
   77 |   typedef basic_string<char>    string;
      |                                 ^~~~~~
In file included 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:
/usr/include/c++/14/string:76:11: note:   'std::pmr::string'
   76 |     using string    = basic_string<char>;
      |           ^~~~~~
a.cc:17:9: error: 'cin' was not declared in this scope; did you mean 'std::cin'?
   17 |         cin >> s;
      |         ^~~
      |         std::cin
/usr/include/c++/14/iostream:62:18: note: 'std::cin' declared here
   62 |   extern istream cin;           ///< Linked to standard input
      |                  ^~~
a.cc:17:16: error: 's' was not declared in this scope
   17 |         cin >> s;
      |                ^
a.cc:19:17: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
   19 |                 cout << "Bad" << 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:19:34: error: 'endl' was not declared in this scope; did you mean 'std::endl'?
   19 |                 cout << "Bad" << endl;
      |                                  ^~~~
      |                                  std::endl
/usr/include/c++/14/ostream:744:5: note: 'std::endl' declared here
  744 |     endl(basic_ostream<_CharT, _Traits>& __os)
      |     ^~~~
a.cc:22:17: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
   22 |                 cout << "Good" << 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:22:35: error: 'endl' was not declared in this scope; did you mean 'std::endl'?
   22 |                 cout << "Good" << endl;
      |                                   ^~~~
      |                                   std::endl
/usr/include/c++/14/ostream:744:5: note: 'std::endl' declared here
  744 |     endl(basic_ostream<_CharT, _Traits>& __os)
      |     ^~~~