View Compilation Error

0_0_24826033_19775.cpp: In function 'int main()':
0_0_24826033_19775.cpp:5:19: error: 'scanf' was not declared in this scope
      scanf("%d",&n);
                   ^
0_0_24826033_19775.cpp:13:22: error: 'printf' was not declared in this scope
       printf("%d\n",r);
                      ^