n = read_line.to_i
s = (1..n).map {
  read_line.chars.map(&.-('a'))
}.select { |s|
  s.each_cons(2).all? { |(i, j)| i <= j }
}.sort_by(&.last)

dp = [0] * 26
s.each do |s|
  dp[s.last] = {dp[s.last], dp[..s.first].max + s.size}.max
end
puts dp.max