Codeforces#295 Div2-A

295-div2-a.rb

# http://codeforces.com/contest/520/problem/A
class Pangram
  def initialize(s)
    @chars = s.downcase.chars
  end

  def is_pangram?
    @chars.uniq.length >= ('a'..'z').to_a.length
  end

  def self.is_pangram?(chars)
    new(chars).is_pangram?
  end
end

n = gets.chomp
s = gets.chomp
puts Pangram.is_pangram?(s) ? 'YES' : 'NO'