import java.util.Scanner;
public class Card{
	public static void main(String[] arg){
		Scanner sc = new Scanner(System.in);
		int n,m,temp,top;
		n = sc.nextInt();
		m = sc.nextInt();
		int[] deck = new int[n];
		for(int i = 0;i<n;i++){
			deck[i] = i + 1;
		}
		for(int i = 0;i<m;i++){
			temp = sc.nextInt()-1;
			top = deck[temp];
			for(int j = 0;j<temp;j++){
				deck[temp-j] = deck[temp-j-1];
			}
			deck[0] = top;
		}
		System.out.println(deck[0]);
	}
}