Code:
while hours >= 0
   {
    while minutes >= 0
       {
        while seconds > 0
           {
            for i = 1 to whatever_is_needed_to_make_second
               {
                // Something to pass time here.
               }
            seconds = seconds - 1;
           }
        seconds  = 60;
        minutes = minutes - 1;
       }
    minutes = 59;
    hours = hours -1;
   }
cout << "Time's up!";