with open('24 (8).txt', 'r') as f:
    data = f.read()


data = data.replace('A', '*').replace('B', '*').split('*')
k_max = 0
for i in range(len(data) - 2):
    items = [data[i], data[i + 1] , data[i + 2]]
    length = sum([len(q) for q in items])
    k_max = max(k_max, length+3)

print(k_max)#200