func main()
	var ss: [][]char :: cui@input().split(" ")
	var N: int :: ss[0].toInt(&)
	var M: int :: ss[1].toInt(&)
	
	var num: []int :: #[N + 1]int
	for i(1, N)
		do num[i] :: i
	end for

	do ss :: cui@input().split(" ")
	for i(0, M - 1)
		var A: int :: ss[i].toInt(&)
		var tmp: int :: num[A]
		for n(A - 1, 1, -1)
			do num[n + 1] :: num[n]
		end for
		do num[1] :: tmp
	end for
	var ans: int :: num[1]
	do cui@print("\{ans}\n")
end func