The information of a project is shown below. Activity A, 7 days, 32 workers, IP = none Activity B, 3 days, 9 workers, IP = none Activity C, 4 days, 34 workers, IP = none Activity D, 3 days, 18 workers, IP = A Activity E, 6 days, 23 workers, IP = B Activity F, 8 day, 28 workers, IP = C The project is completed when activities D, E, and F are finished. The project will be performed using the "latest start and latest finish time" schedule. The number of workers needed on day 3 is