CD=open("24__.txt").readline().strip()
position=[]

for i in range(len(CD) - 1):
    if CD[i:i+2] == 'CD':
        position.append(i)
position.append(len(CD) - 1)

ml = 0
for p, p1 in zip(position, position[161:]):
    ml = max(ml, p1 - p)
print(ml)