View Compilation Error

2_28141_2127981_6885.cpp: In function 'int main()':
2_28141_2127981_6885.cpp:27:9: error: 'cin' was not declared in this scope
  while (cin >> n)f(n)
         ^
2_28141_2127981_6885.cpp:27:9: note: suggested alternative:
In file included from 2_28141_2127981_6885.cpp:1:0:
4.9.2/x86_64-w64-mingw32/include/c++/iostream:60:18: note:   'std::cin'
   extern istream cin;  /// Linked to standard input
                  ^
2_28141_2127981_6885.cpp:27:21: error: 'f' was not declared in this scope
  while (cin >> n)f(n)
                     ^