import re
S = input()
cc = len(S)
pat = re.compile(r'c.*?w.*?w')
i = 0
ans = []
while i < cc:
    mob = pat.search(S,i)
    if mob:
        a, b = mob.span()
        bw = b - a
        ans.append(bw)
    i += 1
if ans == []:
    print(-1)
else:
    print(min(ans))