answer.code: In function ‘void Mul(int*, int*, int*)’:
answer.code:23:9: error: ‘memcpy’ was not declared in this scope
   23 |         memcpy(a,A,(n+1)<<2);
      |         ^~~~~~
answer.code:2:1: note: ‘memcpy’ is defined in header ‘<cstring>’; did you forget to ‘#include <cstring>’?
    1 | #include<iostream>
  +++ |+#include <cstring>
    2 | 
answer.code:25:9: error: ‘memset’ was not declared in this scope
   25 |         memset(c,0,(n+1)<<2);
      |         ^~~~~~
answer.code:25:9: note: ‘memset’ is defined in header ‘<cstring>’; did you forget to ‘#include <cstring>’?