View Compilation Error

0_0_33157536_10773.cpp: In function 'int main()':
0_0_33157536_10773.cpp:75:43: error: wrong number of template arguments (0, should be 1)
         std::sort(a, a + 18, std::greater<>());
                                           ^
In file included from GCC4.9.2/x86_64-w64-mingw32/include/c++/string:48:0,
                 from GCC4.9.2/x86_64-w64-mingw32/include/c++/random:40,
                 from GCC4.9.2/x86_64-w64-mingw32/include/c++/bits/stl_algo.h:66,
                 from GCC4.9.2/x86_64-w64-mingw32/include/c++/algorithm:62,
                 from 0_0_33157536_10773.cpp:3:
GCC4.9.2/x86_64-w64-mingw32/include/c++/bits/stl_function.h:358:12: error: provided for 'template<class _Tp> struct std::greater'
     struct greater : public binary_function<_Tp, _Tp, bool>
            ^