Language: C++

#include<iostream>
using namespace syd;
int main() {
	int N;
	cin >> N;
	if (100 <= N && N <= 111) {
		cout << "111" << endl;
	}
	else if (112 <= N && N <= 222) {
		cout << "222" << endl;
	}
	else if (223 <= N && N <= 333) {
		cout << "333" << endl;
	}
	else if (334 <= N && N <= 444) {
		cout << "444" << endl;
	}
	else if (445 <= N && N <= 555) {
		cout << "555" << endl;
	}
	else if (556 <= N && N <= 666) {
		cout << "666" << endl;
	}
	else if (667 <= N && N <= 777) {
		cout << "777" << endl;
	}
	else if (778<= N && N <= 888) {
		cout << "888" << endl;
	}
	else if (889 <= N && N <= 999) {
		cout << "999" << endl;
	}

}

Compiler output:
a.cc:2:17: error: 'syd' is not a namespace-name
    2 | using namespace syd;
      |                 ^~~
a.cc: In function 'int main()':
a.cc:5:9: error: 'cin' was not declared in this scope; did you mean 'std::cin'?
    5 |         cin >> N;
      |         ^~~
      |         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:7:17: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
    7 |                 cout << "111" << 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:7:34: error: 'endl' was not declared in this scope; did you mean 'std::endl'?
    7 |                 cout << "111" << endl;
      |                                  ^~~~
      |                                  std::endl
In file included from /usr/include/c++/14/iostream:41:
/usr/include/c++/14/ostream:744:5: note: 'std::endl' declared here
  744 |     endl(basic_ostream<_CharT, _Traits>& __os)
      |     ^~~~
a.cc:10:17: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
   10 |                 cout << "222" << 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:10:34: error: 'endl' was not declared in this scope; did you mean 'std::endl'?
   10 |                 cout << "222" << endl;
      |                                  ^~~~
      |                                  std::endl
/usr/include/c++/14/ostream:744:5: note: 'std::endl' declared here
  744 |     endl(basic_ostream<_CharT, _Traits>& __os)
      |     ^~~~
a.cc:13:17: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
   13 |                 cout << "333" << 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:13:34: error: 'endl' was not declared in this scope; did you mean 'std::endl'?
   13 |                 cout << "333" << endl;
      |                                  ^~~~
      |                                  std::endl
/usr/include/c++/14/ostream:744:5: note: 'std::endl' declared here
  744 |     endl(basic_ostream<_CharT, _Traits>& __os)
      |     ^~~~
a.cc:16:17: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
   16 |                 cout << "444" << 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:16:34: error: 'endl' was not declared in this scope; did you mean 'std::endl'?
   16 |                 cout << "444" << endl;
      |                                  ^~~~
      |                                  std::endl
/usr/include/c++/14/ostream:744:5: note: 'std::endl' declared here
  744 |     endl(basic_ostream<_CharT, _Traits>& __os)
      |     ^~~~
a.cc:19:17: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
   19 |                 cout << "555" << 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 << "555" << 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 << "666" << 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:22:34: error: 'endl' was not declared in this scope; did you mean 'std::endl'?
   22 |                 cout << "666" << endl;
      |                                  ^~~~
      |                                  std::endl
/usr/include/c++/14/ostream:744:5: note: 'std::endl' declared here
  744 |     endl(basic_ostream<_CharT, _Traits>& __os)
      |     ^~~~
a.cc:25:17: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
   25 |                 cout << "777" << 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:25:34: error: 'endl' was not declared in this scope; did you mean 'std::endl'?
   25 |                 cout << "777" << endl;
      |                                  ^~~~
      |                                  std::endl
/usr/include/c++/14/ostream:744:5: note: 'std::endl' declared here
  744 |     endl(basic_ostream<_CharT, _Traits>& __os)
      |     ^~~~
a.cc:28:17: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
   28 |                 cout << "888" << 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:28:34: error: 'endl' was not declared in this scope; did you mean 'std::endl'?
   28 |                 cout << "888" << endl;
      |                                  ^~~~
      |                                  std::endl
/usr/include/c++/14/ostream:744:5: note: 'std::endl' declared here
  744 |     endl(basic_ostream<_CharT, _Traits>& __os)
      |     ^~~~
a.cc:31:17: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
   31 |                 cout << "999" << 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:31:34: error: 'endl' was not declared in this scope; did you mean 'std::endl'?
   31 |                 cout << "999" << endl;
      |                                  ^~~~
      |                                  std::endl
/usr/include/c++/14/ostream:744:5: note: 'std::endl' declared here
  744 |     endl(basic_ostream<_CharT, _Traits>& __os)
      |     ^~~~