View Compilation Error

0_0_19553441_12928.cpp: In function 'int main()':
0_0_19553441_12928.cpp:14:30: error: 'memset' was not declared in this scope
           memset(f,0,sizeof f);
                              ^
0_0_19553441_12928.cpp:16:29: error: 'sort' was not declared in this scope
           sort(a+1,a+n+1,cmp);
                             ^