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 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();
        }

        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);
    }
}