View Compilation Error

0_0_18016539_13953.cpp: In function 'int KM(int)':
0_0_18016539_13953.cpp:5:41: error: 'memset' was not declared in this scope
 #define clr(c, o) memset(c, o, sizeof(c)) 
                                         ^
0_0_18016539_13953.cpp:26:6: note: in expansion of macro 'clr'
      clr(ly,0), clr(match, -1);    
      ^