View Compilation Error

0_0_15224259_30696.cpp: In function 'int main()':
0_0_15224259_30696.cpp:8:15: error: 'scanf' was not declared in this scope
  scanf("%d",&n);
               ^
0_0_15224259_30696.cpp:13:20: error: 'printf' was not declared in this scope
     printf("%d\n",o);
                    ^