Language: C++

#include<bits/stdc++.h>

int main(void){
  int sx, sy, tx, ty;
  cin >> sx >> sy >> tx >> ty;
  for(int i=0;i<tx-sx;++i){
    cout << "U";
  }
  for(int i=0;i<ty-sy;++i){
    cout << "R";
  }
  for(int i=0;i<tx-sx;++i){
    cout << "D";
  }
  for(int i=0;i<=ty-sy;++i){
    cout << "L";
  }
  for(int i=0;i<=tx-sx;++i){
    cout << "U";
  }
  for(int i=0;i<=ty-sy;++i){
    cout << "R";
  }
  cout << "DR";
  for(int i=0;i<=tx-sx;++i){
    cout << "D";
  }
  for(int i=0;i<=ty-sy;++i){
    cout << "L";
  }
  cout << "U" << endl;
}


Compiler output:
a.cc: In function 'int main()':
a.cc:5:3: error: 'cin' was not declared in this scope; did you mean 'std::cin'?
    5 |   cin >> sx >> sy >> tx >> ty;
      |   ^~~
      |   std::cin
In file included from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:146,
                 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:7:5: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
    7 |     cout << "U";
      |     ^~~~
      |     std::cout
/usr/include/c++/14/iostream:63:18: note: 'std::cout' declared here
   63 |   extern ostream cout;          ///< Linked to standard output
      |                  ^~~~
a.cc:10:5: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
   10 |     cout << "R";
      |     ^~~~
      |     std::cout
/usr/include/c++/14/iostream:63:18: note: 'std::cout' declared here
   63 |   extern ostream cout;          ///< Linked to standard output
      |                  ^~~~
a.cc:13:5: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
   13 |     cout << "D";
      |     ^~~~
      |     std::cout
/usr/include/c++/14/iostream:63:18: note: 'std::cout' declared here
   63 |   extern ostream cout;          ///< Linked to standard output
      |                  ^~~~
a.cc:16:5: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
   16 |     cout << "L";
      |     ^~~~
      |     std::cout
/usr/include/c++/14/iostream:63:18: note: 'std::cout' declared here
   63 |   extern ostream cout;          ///< Linked to standard output
      |                  ^~~~
a.cc:19:5: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
   19 |     cout << "U";
      |     ^~~~
      |     std::cout
/usr/include/c++/14/iostream:63:18: note: 'std::cout' declared here
   63 |   extern ostream cout;          ///< Linked to standard output
      |                  ^~~~
a.cc:22:5: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
   22 |     cout << "R";
      |     ^~~~
      |     std::cout
/usr/include/c++/14/iostream:63:18: note: 'std::cout' declared here
   63 |   extern ostream cout;          ///< Linked to standard output
      |                  ^~~~
a.cc:24:3: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
   24 |   cout << "DR";
      |   ^~~~
      |   std::cout
/usr/include/c++/14/iostream:63:18: note: 'std::cout' declared here
   63 |   extern ostream cout;          ///< Linked to standard output
      |                  ^~~~
a.cc:31:18: error: 'endl' was not declared in this scope; did you mean 'std::endl'?
   31 |   cout << "U" << 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)
      |     ^~~~