s = input()
res = 114
while "c" in s:
    cidx = s.find("c")
    widx = s.find("w", cidx+1)
    if widx < 0:
        break
    w2idx = s.find("w", widx+1)
    if w2idx > 0:
        res = min(res, w2idx - cidx + 1)
    s = s[cidx+1:]
print(res if res != 114 else -1)