input_line = input()
k = 100
while "c" in input_line:
	find_c = input_line.find("c")
	if "w" in input_line[find_c+1:]:
		find_w = input_line[find_c+1:].find("w")
		if "w" in input_line[find_c+find_w+2:]:
			find_ww = input_line[find_c+find_w+2:].find("w")
			if k > find_ww+find_w+3:
				k = find_ww+find_w+3
			input_line = input_line[find_c+1:]
		else:
			print(-1)
			break
	else:
		print(-1)
		break
if k != 100:
	print(k)