s = input()
c, cw = None, None
ans = float("inf")
for i in range(len(s)):
    if s[i] == "c":
        c = i
    elif s[i] == "w":
        if cw is not None:
            ans = min(ans, i - cw + 1)
        if c is not None:
            cw = c
print([ans, -1][ans == float("inf")])