The information of a project is shown below. Activity A, 7 days, 8 workers, IP = none Activity B, 3 days, 23 workers, IP = none Activity C, 4 days, 12 workers, IP = none Activity D, 3 days, 15 workers, IPA Activity E, 6 days, 11 workers, IP = B Activity F, 8 day, 16 workers, IP = C The project is completed when activities D, E, and F are finished. The project will be performed using the "earliest start and earliest finish time" schedule. The number of workers needed on day 10 is