import sequtils
let S = stdin.readLine
var progress, length = newSeqWith(0, 0)
var best = int.high

for i, s in S:
  case s:
    of 'c':
      progress.add(1)
      length.add(1)
    of 'w':
      for i, v in progress:
        progress[i] += 1
        if progress[i] == 3:
          best = min(length[i], best)
    else:
      discard
  for i, v in length: length[i] += 1

echo [best, -1][int(best == int.high)]