View Compilation Error

0_0_19868302_23620.cpp: In function 'int main()':
0_0_19868302_23620.cpp:15:15: error: 'scanf' was not declared in this scope
  scanf("%d",&n);
               ^
0_0_19868302_23620.cpp:21:11: error: 'getchar' was not declared in this scope
   getchar();
           ^
0_0_19868302_23620.cpp:41:26: error: 'printf' was not declared in this scope
         printf("%d\n",sum);
                          ^