str = input()

valid = False
success_dict = dict()

min_length = 1000
for i in range(len(str)):
    if str[i] == "c":
        w_count = 0
        for j in range(i + 1, len(str)):
            if str[j] == "w":
                w_count += 1
                if w_count == 2:
                    valid = True
                    if j - i + 1 < min_length:
                        min_length = j - i + 1
if valid:
    print(min_length)
else:
    print(-1)