Problem:
Score : 300 points

Problem Statement

Given are an integer X and an integer sequence of length N: p_1, \ldots, p_N.

Among the integers not contained in the sequence p_1, \ldots, p_N (not necessarily positive), find the integer nearest to X, that is, find the integer whose absolute difference with X is the minimum. If there are multiple such integers, report the smallest such integer.

Constraints

1 \leq X \leq 100

0 \leq N \leq 100

1 \leq p_i \leq 100

p_1, \ldots, p_N are all distinct.

All values in input are integers.

Input

Input is given from Standard Input in the following format:

X N
p_1 ... p_N

Output

Print the answer.

Sample Input 1

6 5
4 7 10 6 5

Sample Output 1

8

Among the integers not contained in the sequence 4, 7, 10, 6, 5, the one nearest to 6 is 8.

Sample Input 2

10 5
4 7 10 6 5

Sample Output 2

9

Among the integers not contained in the sequence 4, 7, 10, 6, 5, the ones nearest to 10 are 9 and 11. We should print the smaller one, 9.

Sample Input 3

100 0

Sample Output 3

100

When N = 0, the second line in the input will be empty. Also, as seen here, X itself can be the answer.

Solution in Java (OpenJDK 11.0.6) (judge verdict: Accepted)

import java.util.Scanner;

public class Main{
	public static void main(String[] args) {
		Scanner scn = new Scanner(System.in);
		int x = scn.nextInt(), n = scn.nextInt();
		int[] arr = new int[102];
		for (int i = 0; i < n; i++) {
			arr[scn.nextInt()] = 1;
		}
		if (arr[x] == 0) {
			System.out.println(x);
		} else {
			int left = x - 1, right = x + 1;
			int ans = Integer.MAX_VALUE;
			while (left >= 0 && right < arr.length) {
				if (arr[left] == 0) {
					ans = left;
					break;
				} else {
					left--;
				}
				if (arr[right] == 0) {
					ans = right;
					break;
				} else {
					right++;
				}
			}
			while (left < 0 && right < arr.length) {
				if (arr[right] == 0) {
					ans = right;
					break;
				} else {
					right++;
				}
			}
			while (right >= arr.length && left >= 0) {
				if (arr[left] == 0) {
					ans = left;
					break;
				} else {
					left--;
				}
			}
			System.out.println(ans);
		}
	}
}