View Compilation Error

0_0_21944653_30557.cpp: In function 'int main()':
0_0_21944653_30557.cpp:16:18: error: 'scanf' was not declared in this scope
     scanf("%d",&n);  
                  ^
0_0_21944653_30557.cpp:23:26: error: 'printf' was not declared in this scope
         printf("%d\n",sum);  
                          ^