s = gets.chomp

w_idxs = [] #文字"w"の位置を格納する。
min_len = nil
(s.length-1).downto(0) do |i|
   c = s[i]
   case c
   when "c"
     next unless w_idxs.size >= 2
     len = w_idxs[1] - i + 1
     min_len = len if !min_len || len < min_len
   when "w"
     w_idxs.unshift i
   end
end

puts min_len || -1