# -*- coding: utf-8 -*-

S = raw_input()

hitC = -1
hitW = -1
mn = float("inf")
latestCWStart = -1
for i, s in enumerate(S):
    if s == "c":
        hitC = i
    if s == "w":
        if latestCWStart != -1:
            mn = min(mn, i - latestCWStart + 1)

        hitW = i
        if hitC < hitW:
            latestCWStart = hitC

if mn == float("inf"):
    print -1
else:
    print mn