arr = [] # 配列の初期化
while (gets) # 標準入力があるかぎり実行
  arr << $_.chomp
end
(0..arr.length-1).each do |i|
  arr[i] = arr[i].split
  arr[i] = arr[i].map { |n| n.to_i }
end
arr.each do |n|
  n.push(n[0]+1)
end

# 現在地
present_loc = [1, arr[0][0]]
m = arr[0][2]

arr.delete_at(0)

m.times do
    root_choice_a = arr.select {  |a| a[0] == present_loc[0] && a[1] <= present_loc[1] }
    root_choice_b = arr.select {  |a| a[3] == present_loc[0] && a[2] <= present_loc[1] }
    if root_choice_a.empty? && root_choice_b.empty?
        break
    end
    root_choice = root_choice_a + root_choice_b
    root = root_choice.map {
        |a|
        if a[0] == present_loc[0]
            a[1]
        else
            a[2]
        end
        }
    root_index = root.index(root.max)

    action = root_choice[root_index]
    if present_loc[0] == action[0]
      loc_0 = action[3]
      loc_1 = action[2]
    else
      loc_0 = action[0]
      loc_1 = action[1]
    end
    present_loc[0] = loc_0
    present_loc[1] = loc_1
    arr.delete(action)
end

puts present_loc[0]