N = gets.to_i
Q = []

N.times do |i|
  a, b = gets.split.map(&:to_i)

  Q << [i, [a, b]]
end

Q.sort_by! { |_i, (a, b)| [a, b].min }
checked = Array.new(N + 1, false)
ans = Array.new(N)

Q.each do |i, (a, b)|
  if not checked[a]
    ans[i] = a
    checked[a] = true
  elsif not checked[b]
    ans[i] = b
    checked[b] = true
  else
    puts 'No'
    exit
  end
end

puts 'Yes'
puts ans