ss = input()
str_count = 0
str_count_start = False
w_count = 0

for s in ss:
    if w_count == 2:
        break
    elif s == "c":
        str_count_start = True
    elif str_count_start and s == "w":
        w_count += 1
    if str_count_start:
        str_count += 1
if w_count != 2:
    print(-1)
else:
    print(str_count)