foo.cc: In function 'int main()':
foo.cc:13:50: error: wrong number of template arguments (0, should be 1)
   13 |         priority_queue <int, vector<int>, greater<>> a;
      |                                                  ^
In file included from /nix/store/jdc41bl531bw84wi82y6gvij34q5m24a-gcc-11.3.0/include/c++/11.3.0/string:48,
                 from /nix/store/jdc41bl531bw84wi82y6gvij34q5m24a-gcc-11.3.0/include/c++/11.3.0/bits/locale_classes.h:40,
                 from /nix/store/jdc41bl531bw84wi82y6gvij34q5m24a-gcc-11.3.0/include/c++/11.3.0/bits/ios_base.h:41,
                 from /nix/store/jdc41bl531bw84wi82y6gvij34q5m24a-gcc-11.3.0/include/c++/11.3.0/ios:42,
                 from /nix/store/jdc41bl531bw84wi82y6gvij34q5m24a-gcc-11.3.0/include/c++/11.3.0/ostream:38,
                 from iostream:39:
/nix/store/jdc41bl531bw84wi82y6gvij34q5m24a-gcc-11.3.0/include/c++/11.3.0/bits/stl_function.h:385:12: note: provided for 'template<class _Tp> struct std::greater'
  385 |     struct greater : public binary_function<_Tp, _Tp, bool>
      |            ^~~~~~~
foo.cc:13:51: error: template argument 3 is invalid
   13 |         priority_queue <int, vector<int>, greater<>> a;
      |                                                   ^~
foo.cc:14:47: error: wrong number of template arguments (0, should be 1)
   14 |         priority_queue <int, vector<int>, less<>> b;
      |                                               ^
In file included from /nix/store/jdc41bl531bw84wi82y6gvij34q5m24a-gcc-11.3.0/include/c++/11.3.0/string:48,
                 from /nix/store/jdc41bl531bw84wi82y6gvij34q5m24a-gcc-11.3.0/include/c++/11.3.0/bits/locale_classes.h:40,
                 from /nix/store/jdc41bl531bw84wi82y6gvij34q5m24a-gcc-11.3.0/include/c++/11.3.0/bits/ios_base.h:41,
                 from /nix/store/jdc41bl531bw84wi82y6gvij34q5m24a-gcc-11.3.0/include/c++/11.3.0/ios:42,
                 from /nix/store/jdc41bl531bw84wi82y6gvij34q5m24a-gcc-11.3.0/include/c++/11.3.0/ostream:38,
                 from iostream:39:
/nix/store/jdc41bl531bw84wi82y6gvij34q5m24a-gcc-11.3.0/include/c++/11.3.0/bits/stl_function.h:395:12: note: provided for 'template<class _Tp> struct std::less'
  395 |     struct less : public binary_function<_Tp, _Tp, bool>
      |            ^~~~
foo.cc:14:48: error: template argument 3 is invalid
   14 |         priority_queue <int, vector<int>, less<>> b;
      |                                                ^~
foo.cc:19:19: error: request for member 'push' in 'a', which is of non-class type 'int'
   19 |                 a.push(temp);
      |                   ^~~~
foo.cc:20:19: error: request for member 'push' in 'b', which is of non-class type 'int'
   20 |                 b.push(temp);
      |                   ^~~~
foo.cc:26:25: error: request for member 'top' in 'a', which is of non-class type 'int'
   26 |                 top = a.top();
      |                         ^~~
foo.cc:27:28: error: request for member 'top' in 'b', which is of non-class type 'int'
   27 |                 bottom = b.top();
      |                            ^~~
foo.cc:30:27: error: request for member 'pop' in 'b', which is of non-class type 'int'
   30 |                         b.pop();
      |                           ^~~
foo.cc:36:27: error: request for member 'pop' in 'b', which is of non-class type 'int'
   36 |                         b.pop();
      |                           ^~~
foo.cc:37:27: error: request for member 'pop' in 'a', which is of non-class type 'int'
   37 |                         a.pop();
      |                           ^~~
foo.cc:40:23: error: request for member 'size' in 'a', which is of non-class type 'int'
   40 |                 if (a.size() == n / 2 || b.size() == n / 2)
      |                       ^~~~
foo.cc:40:44: error: request for member 'size' in 'b', which is of non-class type 'int'
   40 |                 if (a.size() == n / 2 || b.size() == n / 2)
      |                                            ^~~~

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