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

(N, M), A = $<.map{|x| x.chomp.split.map(&:to_i)}

cards = (0..N).to_a

M.times do |i|
	cards[0] = cards[A[i]]
	A[i].downto(1) do |j|
		cards[j] = cards[j - 1]
	end
end

puts cards[1]