cww = [-1, -1]
cand = [-1]
for i, char in enumerate(input()):
    if char == "c":
        cww[0] = i
    if char == "w":
        if cww[1] != -1:
            cand += [i-cww[1]+1]
        if cww[0] != -1:
            cww[1] = cww[0]

print(-1 if len(cand) == 0 else min(cand))