View Compilation Error

0_0_35388976_147.cpp: In function 'int main()':
0_0_35388976_147.cpp:67:24: error: too few arguments to function 'void* memset(void*, int, size_t)'
   memset(top,sizeof top);
                        ^
In file included from GCC4.9.2/x86_64-w64-mingw32/include/c++/cstring:42:0,
                 from 0_0_35388976_147.cpp:5:
GCC4.9.2/x86_64-w64-mingw32/include/string.h:43:18: note: declared here
   void * __cdecl memset(void *_Dst,int _Val,size_t _Size);
                  ^