let () =
  let rec search str start target count next =
    if start < String.length str then
      if str.[start] = 'c' && target = 'c' then search str (start+1) 'W' 1 next
      else if str.[start] = 'w' && target = 'W' then search str (start+1) 'w' (count+1) next
      else if str.[start] = 'w' && target = 'w' then (next,count+1)
      else if str.[start] = 'c' && next = -1 then search str (start+1) target (count+1) start
      else search str (start+1) target (count+1) next
    else (next, -1) in
  Scanf.scanf "%s\n" @@ fun s ->
  let start = ref 0 in
  let ans = ref (String.length s + 1) in
  while !start <> -1 do
    let (next, count) = search s !start 'c' 0 (-1) in
    if !ans > count && count > 0 then ans := count; start := next;
  done;
  Printf.printf "%d\n" (if !ans = (String.length s + 1) then -1 else !ans)