def main():
  s = list(input())

  if not (False in [i not in "c" for i in s] and False in [i not in "w" for i in s]):
    print(-1)
  else:
    pass

  for i, word in enumerate(s):
    if word == "c":
      break
    else:
      pass
  del s[:i]

  w_count = 0
  for i, word in enumerate(s):
    if word == "w" and w_count == 0:
      w_count += 1
    elif word == "w" and w_count == 1:
      w_count += 1
      break
    else:
      pass
  if w_count == 2:
    print(i+1)
  else:
    print(-1)


if __name__ == "__main__":
  main()