import java.util.*;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int x =sc.nextInt();
		int n =sc.nextInt();
		int min=0;
		int max=0;
		ArrayList p = new ArrayList<>();
		
	
		for(int i=0;i<n;i++) {
			p.add(sc.nextInt());
		}

		if(!(p.contains(x))) {
			System.out.println(x);
			System.exit(0);
		}
		
		
		for(int i=1;i<p.size();i++) {
			if(!(p.contains(x-i))) {
				System.out.println(x-i);
				System.exit(0);
			}
			else if(!(p.contains(x+i))) {
				System.out.println(x+i);
				System.exit(0);
				
			}
		}
		System.out.println(0);
		sc.close();
	}
}

/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz