import sys

sample = list(sys.stdin.readline().rstrip('\n'))

count = 0
isOrdered = True

while (isOrdered):
	max_seq = 0
	seq = 1

	last = sample[0]

	start = 0
	end = -1

	max_start, max_end = 0,-1
	for i in range(1,len(sample)):
		
		if last != sample[i] and start:
			seq += 1
		elif start:
			if seq % 2 == 0:
				end = i-1
				if seq > max_seq:
					max_seq = seq
					max_start = start
					max_end = end
			else:
				end = i-2
				if seq > max_seq:
					max_seq = seq-1
					max_start = start
					max_end = end
		if last == sample[i]:
			start = i
			seq = 1
		last = sample[i]
	
	if start:
			if seq % 2 == 0:
				end = i
				if seq > max_seq:
					max_seq = seq
					max_start = start
					max_end = end
			else:
				end = i-1
				if seq > max_seq:
					max_seq = seq-1
					max_start = start
					max_end = end
	
	rotated = sample[max_start:max_end+1]
	if rotated:
		sample = sample[0:max_start]+rotated[::-1]+sample[max_end+1:]
		count += 1
	if max_seq == 0:
		isOrdered = False

print(count)