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: Wrong Answer)

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.IOException;

public class Main {
  public static void main(String[] args) throws IOException {
    BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
    String[] str = in.readLine().split(" ");
    int x = Integer.parseInt(str[0]);
    int n = Integer.parseInt(str[1]);
    int[] p = new int[n];
    int ans = 0;
    if(n!=0) {
      str = in.readLine().split(" ");
      int min = 1000;
      int[] ary = new int[100];
      for(int i=0; i<100; i++) {
        ary[i]=i+1;
      }
      for(int i=0; i<n; i++) {
        p[i] = Integer.parseInt(str[i]);
        for(int j=0; j<100; j++) {
          if(p[i]==ary[j]){
            ary[j]=0;
            break;
          }
        }
      }
      for(int i=0; i<100; i++) {
        if(ary[i]!=0) {
          if(ary[i]>=x){
            if(ary[i]-x<min){
              min = ary[i]-x;
              ans = ary[i];
            }
          } else{
            if(x-ary[i]<min){
              min = x-ary[i];
              ans = ary[i];
            }
          }
        }
      }
    }
    System.out.println(n==0?x:ans);
  }
}