import java.util.*;

class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        int m = in.nextInt();
        int[] a = new int[m];
        for(int i=0; i<m; i++) a[i] = in.nextInt();

        int[] c = new int[n];
        for(int i=0; i<n; i++) c[i] = i+1;

        for(int i=0; i<m; i++) {
            int t = a[i];
            int top = c[a[i]-1];
            //            System.out.print(c[0]+" ");
            for(int j=t-1; j>=1; j--) {
                int temp = c[j-1];
                c[j] = temp;
                //                System.out.print(c[j-1]+" ");
            }
            c[0] = top;
            //            System.out.println();
        }

        System.out.println(c[0]);
    }
}