s = input()
start_found = False
w_first = False
for i in range(len(s)):
  if s[i] == 'c':
    start = i
    start_found = True
  if s[i] == 'w':
    if start_found:
      w_first = True
    
    if w_first == True:
      end = i

if end:
  print(end - start + 1)
else:
  print(-1)