# frozen_string_literal: true

def solve(t_and_s)
  l = []
  r = []
  t_and_s.each do |t, s|
    case t
    when '0'
      r << s
    when '1'
      l << s
    end
  end
  (l.reverse + r).join
end

N = gets.to_i
T = N.times.map { gets.chomp.split }

RESULT = solve(T)

puts RESULT