import java.util.LinkedList;
import java.util.Scanner;

public class No_123second {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		LinkedList<Integer> card = new LinkedList<Integer>();
		int n = sc.nextInt();
		int m = sc.nextInt();
		int[] shuffle = new int[m];

		for (int i = 1; i <= n; i++) {
			card.add(i);
		}

		for (int i = 0; i < m; i++) {
			shuffle[i] = sc.nextInt();
		}

		for (int s : shuffle) {
			int i = card.remove(s - 1);
			card.offerFirst(i);
		}

		System.out.println(card.peek());
		sc.close();

	}

}