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

S = raw_input()

hit = [-1] * 2
mn = float("inf")
latestCWStart = -1
for i, s in enumerate(S):
    if s == "c":
        hit[0] = i
    if s == "w":
        if latestCWStart != -1:
            mn = min(mn, i - latestCWStart + 1)

        hit[1] = i
        if hit[0] < hit[1]:
            latestCWStart = hit[0]

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