s = input()
c_found = False
w_count = 0
sum_count = 0
ans = []
for i in range(len(s)):
  if w_count == 2:
    break
  if s[i] == 'c':
    c_found = True

  if c_found:
    if s[i] == 'w' and w_count < 2:
      w_count += 1
  
  sum_count += 1

if w_count == 2:
  print(sum_count)
else:
  print(-1)