Language: C++

#include <bits/stdc++.h>
uaing namespace std;

int main() {
  int N;
  cin >> N;
  vector<double> x(N), y(N);
  for(int i=0; i<N; ++i) cin >> x[i] >> y[i];
  
  using P = pair<double, int>;
  for(int i=0; i<N; ++i) {
    if(x[i] == 0 && y[i] == 0) r[i] = 0;
    else r[i] = atan2(y[i], x[i]);
  }
  sort(begin(r), end(r));
  
  double res = 0.0
  for(int l=0; l<N; ++l) {
    for(int r=1; r<=N; ++r) {
      double X = 0, Y = 0;
      for(int i=l; i<r; ++i) {
        int c = r[i].second;
        X += x[c];
        Y += y[c];
      }
      res = max(res, sqrt(X * X + Y * Y));
    }
  }
  cout << fixed << setprecision(10) << res <<endl;
}

Compiler output:
a.cc:2:1: error: 'uaing' does not name a type
    2 | uaing namespace std;
      | ^~~~~
a.cc: In function 'int main()':
a.cc:6:3: error: 'cin' was not declared in this scope; did you mean 'std::cin'?
    6 |   cin >> N;
      |   ^~~
      |   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:7:3: error: 'vector' was not declared in this scope
    7 |   vector<double> x(N), y(N);
      |   ^~~~~~
a.cc:7:3: note: suggested alternatives:
In file included from /usr/include/c++/14/vector:66,
                 from /usr/include/c++/14/functional:64,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:53:
/usr/include/c++/14/bits/stl_vector.h:428:11: note:   'std::vector'
  428 |     class vector : protected _Vector_base<_Tp, _Alloc>
      |           ^~~~~~
/usr/include/c++/14/vector:93:13: note:   'std::pmr::vector'
   93 |       using vector = std::vector<_Tp, polymorphic_allocator<_Tp>>;
      |             ^~~~~~
a.cc:7:10: error: expected primary-expression before 'double'
    7 |   vector<double> x(N), y(N);
      |          ^~~~~~
a.cc:8:33: error: 'x' was not declared in this scope
    8 |   for(int i=0; i<N; ++i) cin >> x[i] >> y[i];
      |                                 ^
a.cc:8:41: error: 'y' was not declared in this scope
    8 |   for(int i=0; i<N; ++i) cin >> x[i] >> y[i];
      |                                         ^
a.cc:10:13: error: 'pair' does not name a type
   10 |   using P = pair<double, int>;
      |             ^~~~
a.cc:12:8: error: 'x' was not declared in this scope
   12 |     if(x[i] == 0 && y[i] == 0) r[i] = 0;
      |        ^
a.cc:12:21: error: 'y' was not declared in this scope
   12 |     if(x[i] == 0 && y[i] == 0) r[i] = 0;
      |                     ^
a.cc:12:32: error: 'r' was not declared in this scope
   12 |     if(x[i] == 0 && y[i] == 0) r[i] = 0;
      |                                ^
a.cc:13:10: error: 'r' was not declared in this scope
   13 |     else r[i] = atan2(y[i], x[i]);
      |          ^
a.cc:15:14: error: 'r' was not declared in this scope
   15 |   sort(begin(r), end(r));
      |              ^
a.cc:15:8: error: 'begin' was not declared in this scope
   15 |   sort(begin(r), end(r));
      |        ^~~~~
a.cc:15:8: note: suggested alternatives:
In file included from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:166:
/usr/include/c++/14/valarray:1238:5: note:   'std::begin'
 1238 |     begin(const valarray<_Tp>& __va) noexcept
      |     ^~~~~
In file included from /usr/include/c++/14/filesystem:53,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:200:
/usr/include/c++/14/bits/fs_dir.h:608:3: note:   'std::filesystem::__cxx11::begin'
  608 |   begin(recursive_directory_iterator __iter) noexcept
      |   ^~~~~
a.cc:15:18: error: 'end' was not declared in this scope
   15 |   sort(begin(r), end(r));
      |                  ^~~
a.cc:15:18: note: suggested alternatives:
/usr/include/c++/14/valarray:1265:5: note:   'std::end'
 1265 |     end(const valarray<_Tp>& __va) noexcept
      |     ^~~
/usr/include/c++/14/bits/fs_dir.h:613:3: note:   'std::filesystem::__cxx11::end'
  613 |   end(recursive_directory_iterator) noexcept
      |   ^~~
a.cc:15:3: error: 'sort' was not declared in this scope; did you mean 'std::sort'?
   15 |   sort(begin(r), end(r));
      |   ^~~~
      |   std::sort
In file included from /usr/include/c++/14/algorithm:86,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:51:
/usr/include/c++/14/pstl/glue_algorithm_defs.h:296:1: note: 'std::sort' declared here
  296 | sort(_ExecutionPolicy&& __exec, _RandomAccessIterator __first, _RandomAccessIterator __last);
      | ^~~~
a.cc:18:3: error: expected ',' or ';' before 'for'
   18 |   for(int l=0; l<N; ++l) {
      |   ^~~
a.cc:18:16: error: 'l' was not declared in this scope
   18 |   for(int l=0; l<N; ++l) {
      |                ^
a.cc:29:3: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
   29 |   cout << fixed << setprecision(10) << res <<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:29:11: error: 'fixed' was not declared in this scope
   29 |   cout << fixed << setprecision(10) << res <<endl;
      |           ^~~~~
a.cc:29:11: note: suggested alternatives:
In file included from /usr/include/c++/14/streambuf:43,
                 from /usr/include/c++/14/bits/streambuf_iterator.h:35,
                 from /usr/include/c++/14/iterator:66,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:54:
/usr/include/c++/14/bits/ios_base.h:1104:3: note:   'std::fixed'
 1104 |   fixed(ios_base& __base)
      |   ^~~~~
In file included from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:198:
/usr/include/c++/14/charconv:622:21: note:   'std::chars_format::fixed'
  622 |     scientific = 1, fixed = 2, hex = 4, general = fixed | scientific
      |                     ^~~~~
a.cc:29:20: error: 'setprecision' was not declared in this scope; did you mean 'std::setprecision'?
   29 |   cout << fixed << setprecision(10) << res <<endl;
      |                    ^~~~~~~~~~~~
      |                    std::setprecision
In file included from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:143:
/usr/include/c++/14/iomanip:202:3: note: 'std::setprecision' declared here
  202 |   setprecision(int __n)
      |   ^~~~~~~~~~~~
a.cc:29:46: error: 'endl' was not declared in this scope; did you mean 'std::endl'?
   29 |   cout << fixed << setprecision(10) << res <<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)
      |     ^~~~