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 1.8.0) (judge verdict: Accepted)

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

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

		int x = sc.nextInt();
		int n = sc.nextInt();
if(n==0){System.out.println(x);}else{
		int p[] = new int[n];
		int q[] = new int[102 - n];
		q[0] = 0;
		q[101 - n] = 101;
		for (int i = 0; i < n; i++) {
			p[i] = sc.nextInt();
		}

		Arrays.sort(p);
		int look = 0;
		int lookb = 0;
		for (int i = 0; i <= 101; i++) {
			if (!(p[lookb] == i)) {
				// System.out.println("!"+i);
				q[look] = i;
				look++;

			} else {
				lookb++;
				if (lookb >= n) {
					lookb--;
				}
			}
		}
/*		for (int i = 0; i < q.length; i++) {
			System.out.println(q[i]);
		}
*/
		int sub=x;
		int ans=0;
for(int i=0;i<q.length;i++){
if(sub>Math.abs(q[i]-x)){
	sub=Math.abs(q[i]-x);
	ans=q[i];
}
}System.out.println(ans);
}
	}
}