View Compilation Error

0_0_33251281_2029.cpp: In function 'int main()':
0_0_33251281_2029.cpp:21:24: error: 'scanf' was not declared in this scope
     while(scanf("%d",&n)==1)
                        ^
0_0_33251281_2029.cpp:27:29: error: 'sprintf' was not declared in this scope
             sprintf(s,"%d",r);
                             ^
0_0_33251281_2029.cpp:32:26: error: 'printf' was not declared in this scope
         printf("%d\n",sum);
                          ^