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.*;

public class Main{
  public static void main(String[] args){

    Scanner scan = new Scanner(System.in);
    int x = scan.nextInt();
    int n = scan.nextInt();
    if (n == 0){
      System.out.println(x);
      return;
    }
    int [] a = new int[103];

    for (int i=0;i<103;i++){
      a[i] = i-1;
    }

    for (int j=0;j<n;j++){
      int t = scan.nextInt();
      a[t+1] = -2;
    }

    if (a[x+1] != -2){
      System.out.println(x);
      return;
    }

    int small = 104;
    int val = -3;
    for (int p=0;p<103;p++){
      if (a[p] == -2){
        continue;
      }
      int abs = x-a[p];
      if (abs == 0){
        System.out.println(x);
        return;
      }

      if (abs < 0){
        abs = -abs;
      }
      if (abs < small){
        small = abs;
        val = a[p];
      }
    }

    System.out.println(val);
  }
}