ls = list(input())

res = 0
try:
    place_1 = ls.index('c') + 1
    place_2 = ls.index('w', place_1) + 1
    place_3 = ls.index('w', place_2) + 1
    if 'c' in ls[place_1:place_2]:
        ls.reverse()
        place_1 = len(ls) - ls.index('c', -place_2, -place_1)
    print(place_3 - place_1 + 1)

except ValueError:
    print(-1)