View Compilation Error

0_0_36074306_12964.cpp: In function 'int main()':
0_0_36074306_12964.cpp:5:19: error: 'scanf' was not declared in this scope
     scanf("%d", &n);
                   ^
0_0_36074306_12964.cpp:6:18: error: 'getchar' was not declared in this scope
     for (getchar(), i = 0; i < n; ++i)
                  ^
0_0_36074306_12964.cpp:14:58: error: 'sprintf' was not declared in this scope
             if (num != 1) k += sprintf(buf + k, "%d", num);
                                                          ^
0_0_36074306_12964.cpp:17:44: error: 'printf' was not declared in this scope
         printf("%s\n", &(buf[k] = '\0') - k);
                                            ^