View Compilation Error

0_0_23261335_18234.cpp: In function 'int main()':
0_0_23261335_18234.cpp:3:20: error: 'scanf' was not declared in this scope
  while(scanf("%d",a)!=0)
                    ^
0_0_23261335_18234.cpp:14:22: error: 'printf' was not declared in this scope
      printf("%d",&sum);
                      ^