import java.math.*;
import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int m = sc.nextInt();
        int[] ca = new int[n];
        for(int i=0;i<n;i++){
        	ca[i]=i+1;
        }
        for(int i=0;i<m;i++){
        	int a = sc.nextInt();
        	int temp = ca[a-1];
        	for(int j=a-1;j>=1;j--){
        		ca[j]=ca[j-1];
        	}
        	ca[0]=temp;
        }
        System.out.println(ca[0]);
    }
}