There are 3 RSM branches in Math City. The branches are called R, S, and M. Arty plans a 5-day visit to Math City and wants to visit each branch
She will visit one branch per day, which means that Arty will visit one or more
branches more than once, possibly on consecutive days.
How many different schedules can the RSM students prepare for Arty?

One possible schedule is R -S-S-M-R, where Arty visits branch R on the first
and fifth days, branch S on the second and third days, and branch M on the fourth
day.