n = gets.to_i
ans = [0,1,2,3,4,5,6,7,8,9].map(&:to_s)
n.times do
  a,b,c,d,r = gets.split
  if r == 'NO'
    ans -= [a,b,c,d]
  else
    ans = a, b, c, d
  end
end
puts ans.first