S = input().strip()

lst1 = [n for n, i in enumerate(S) if i == 'c']
lst2 = [n for n, i in enumerate(S) if i == 'w' and n > lst1[0]]

if len(lst2) < 2:
  print(-1)
  exit(0)

lst = [i for i in lst1 if i < lst2[0]]
if len(lst) == 0:
  print(-1)
  exit(0)
else:
  pos1 = lst[-1]

pos2 = lst2[1]

print(pos2 - pos1 + 1)