S = input().strip()

lst = []

for i in range(len(S)):
  if S[i] == 'c':
    tmp = S.find('w', S.find('w', i + 1) + 1) - i + 1
    if tmp > 0:
      lst.append(tmp)

lst = sorted(lst)

#print(lst)
if len(lst) == 0:
  print('-1')
else:
  print(lst[0])