import sequtils

let s = readLine stdin
var cs, ws = newSeq[int]()

for i, v in s:
  if v == 'c': cs.add i
  if v == 'w': ws.add i

if cs.len == 0:
  echo -1
  quit()

var ans = int.high

for c in cs:
  ws.keepItIf(it > c)
  if ws.len >= 2:
    ans = ans.min succ ws[1].pred c

echo if ans == int.high: -1 else: ans