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

public class Main {
	public static void main(String[] args){
		
		Scanner sc = new Scanner(System.in);

		// 整数の入力
		int a = sc.nextInt();//最もこれに近い整数を求める
		int b = sc.nextInt();//整数の数

		List<Integer> list = new ArrayList<>();
		
		for (int i = 0; i < b; i++) {
			list.add(sc.nextInt());
		}
		
		int index = 0;
		boolean flag = true;
		
		while (flag && -100 <= index && index <= 100) {
			a -= index;
			if (list.indexOf(a) == -1) {
				System.out.println(a);
				flag = false;
			} else {
				if (index >= 0) {
					index++;
				} else {
					index--;
				}
				if (index != 1) {
					index *= -1;
				}
				
			}
		}
	}
}
/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