moves = input()
moves = list(moves)

place = 1

for move in list(moves):
    if place == 1 and move == 'A':
        place = 2
    elif place == 2 and move == 'A': 
        place = 1
    elif place == 1 and move == 'C':
        place = 3
    elif place == 3 and move  == 'C':
        place = 1
    elif place == 2 and move  == 'B':
        place = 3
    elif place == 3 and move == 'B':
        place = 2

print(place)