S = input()

indexw = [i for i, x in enumerate(S) if x == "w"]
indexc = [i for i, x in enumerate(S) if x == "c"]
chikuwa = []

for i in indexc:
    for j in range(100):
        if len(indexw) > 0:
            if i >= indexw[0]:
                indexw.pop(0)
            else:
                break
    if len(indexw) >= 2:
        chikuwa.append(indexw[1] - i + 1)

if len(chikuwa) <= 0:
    print(-1)
else:
    print(min(chikuwa))