s = input()

import re

r = re.compile(r'c[^cw]*w[^w]*w')

a = list()
m = r.search(s)
if(m):
    while True:
        a.append(m.group())
        m=r.search(s,m.start()+1)
        if not m:
            break

if len(a)==0:
    print(-1)
else:
    b = min([len(i) for i in a])
    print(b)