#! ruby
# yukicoder My Practice
# author: Leonardone @ NEETSDKASU

N = gets.to_i

enables = ('0'..'9').to_a

N.times do
    *abcd, r = gets.chomp.split
    if r == 'NO'
        enables -= abcd
    else
        enables &= abcd
    end
end

puts enables.first