import java.util.*;
public class card{
	public static void main(String... args){
		Scanner scan = new Scanner(System.in);
		int n = scan.nextInt();
		int m = scan.nextInt();
		ArrayList<Integer> list = new ArrayList<Integer>();
		for(int i = 1; i <= n; i++){
			list.add(i);
		}
		int[] shuffle = new int[m];
		for(int i = 0; i < m; i++){
			shuffle[i] = scan.nextInt();
		}
		System.out.println(cardShuffle(list,shuffle));
	}
	public static int cardShuffle(ArrayList<Integer> list,int[] shuffle){
		for(int i = 0;i < shuffle.length; i++){
			int now = list.get(shuffle[i]);
			list.remove(shuffle[i]);
			list.add(0,now);
		}

		return list.get(0);
	}
}