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

s = list(input())

findc = True
findFW = False
findSW = False
first = 0
end = 0
ans = 999999

for i in range(len(s)):
    if findc:
        if s[i] == "c":
            first = i
            findc = False
            findFW = True
    elif findFW:
        if s[i] == "w":
            findFW = False
            findSW = True
    elif findSW:
        if s[i] == "w":
            end = i
            findSW = False
            findc = True
            ans = min(ans,end-first+1)

if ans == 999999:
    ans = -1

print(ans)