/in/foo.cc: In function 'int main()':
/in/foo.cc:4:5: error: 'cin' was not declared in this scope
     cin >> length >> time;
     ^~~
/in/foo.cc:16:9: error: 'cout' was not declared in this scope
         cout << 13;
         ^~~~
/in/foo.cc:20:36: error: 'printf' was not declared in this scope
         printf("%.1f\n", float(ans));
                                    ^