s=gets.chomp.chars
a=1e9
(0...s.size).each{|i|(i...s.size).each{|j|k=['w','w','c']
s[i..j].each{|c|k.pop if k[-1]==c}
a=[a,s[i..j].size].min if k.empty?}}
p a>1e8?-1:a