S = str(input())

def has_filled_c(chiwawa_index_dict):
	if chiwawa_index_dict["c"] != 0:
		return True
		
def has_filled_first_w(chiwawa_index_dict):
	if chiwawa_index_dict["first_w"] != 0:
		return True
		
def has_filled_second_w(chiwawa_index_dict):
	if chiwawa_index_dict["second_w"] != 0:
		return True

chiwawa_index_dict = {"c": 0, "first_w": 0, "second_w": 0}
for i, word in enumerate(S):
	if word == "c" and not has_filled_c(chiwawa_index_dict):
		chiwawa_index_dict["c"] = i
	elif word == "w" and has_filled_c(chiwawa_index_dict) and not has_filled_first_w(chiwawa_index_dict):
		chiwawa_index_dict["first_w"] = i
	elif word == "w" and has_filled_c(chiwawa_index_dict) and has_filled_first_w(chiwawa_index_dict) and not has_filled_second_w(chiwawa_index_dict):
		chiwawa_index_dict["first_w"] = i
		break
		
if has_filled_second_w(chiwawa_index_dict):
	print(-1)
else:
	print(chiwawa_index_dict["second_w"] - chiwawa_index_dict["c"])