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

dp = [0] * 26
s.each do |s|
  f = s.first - 'a'
  l = s.last - 'a'
  dp[l] = {dp[l], (dp[..f].max? || 0) + s.size}.max
end
puts dp.max