import java.util.Scanner;
import java.util.Arrays;

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

        int x = sc.nextInt();
        int n = sc.nextInt();
        int[] p = new int[n];
        for(int i = 0; i<n; i++){
            p[i] = sc.nextInt();
        }

        Arrays.sort(p);
        int ans = -100000000;
        int ansLow, ansHigh;
        int count = 0;
        int matchNotAns = -1000000000;

        for(int j = 0; j<1000; j++){
            for(int k = 0; k<n; k++){
                if(x - j == p[k]){
                    count++;
                    matchNotAns = p[k];
                }
                else if(x + j == p[k]){
                    count++;
                    matchNotAns = p[k];
                }
            }
            if(count == 1 && j!=0){
                if(matchNotAns == x - j){
                    ans = x + j;
                }
                else if(matchNotAns == x + j){
                    ans = x - j;
                }
                break;
            }
            else if(count == 0){
                ans = x - j;
                break;
            }
            count = 0;
        }

        System.out.println(ans);
    }
}
/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