Conditional formating

i have a row of initials:
MM MM MM MM LL LL LL BB XX XX MM CC CC CC, each pair is a column
these correspond to booking dates, so if the initial next to it is the same make it one color,
MM MM MM MM, LL LL LL, BB, etc. > this would be three colors (the initials can be any combination.
ie: MM booked 4 days, LL 3 days, BB one day.

so at a glance I can tell by color how long is the contiguous stay.

note the MM in front of the CC's is not necessarily part of the first MM's