View Compilation Error

0_0_36750038_21196.cpp: In function 'int main()':
0_0_36750038_21196.cpp:5:2: error: 'set' was not declared in this scope
  set<int> pq;
  ^
0_0_36750038_21196.cpp:5:2: note: suggested alternative:
In file included from GCC4.9.2/x86_64-w64-mingw32/include/c++/set:61:0,
                 from 0_0_36750038_21196.cpp:2:
GCC4.9.2/x86_64-w64-mingw32/include/c++/bits/stl_set.h:90:11: note:   'std::set'
     class set
           ^
0_0_36750038_21196.cpp:5:6: error: expected primary-expression before 'int'
  set<int> pq;
      ^
0_0_36750038_21196.cpp:7:3: error: 'pq' was not declared in this scope
   pq.clear();
   ^
0_0_36750038_21196.cpp:18:7: error: expected primary-expression before 'int'
   set<int>::iterator it;
       ^
0_0_36750038_21196.cpp:19:3: error: 'it' was not declared in this scope
   it=pq.begin();
   ^