require 'set'
  count = gets.to_i
  
  i=[]
  count.times do 
  i << gets.chomp.split("\n").map{|a| a.split(" ")}
end

  candidates = ("0".."9").to_set
  i.each do |a|

    if a.last == "YES"
      candidates = candidates.intersection a
    else
      candidates = candidates.difference a
    end
  end

  puts candidates.first