INPUT column value can be A or B or C

REQUIRED OUTPUT value based on condition as follows

condition(1)if INPUT value A then REQUIRED OUTPUT A

condition(2)if INPUT value C then REQUIRED OUTPUT C

condition(3.i)if INPUT value B and B present after C then REQUIRED OUTPUT C

condition(3.ii.a)if INPUT value B and B present after A and upto 3 times B then REQUIRED OUTPUT A

condition(3.ii.b)if INPUT value B and B present after A and after 3 times B then REQUIRED OUTPUT C