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 sc =new Scanner(System.in);
    int X =sc.nextInt();
    int N =sc.nextInt();
    int P[] =new int[N];
    int R[] =new int[N];
    int Q[] =new int[100];
    int x=0;
    Q[0]=1;
    for(int j=1;j<100;j++){
      Q[j]=2;}
    for(int i=0;i<N;i++){
      P[i]=sc.nextInt();
      R[i]=Math.abs(P[i]-X);
      Q[R[i]]=Q[R[i]]-1;}
    for(int k=0;k<100;k++){
      if(Q[k]==2){System.out.println(X-k);System.exit(0);}
      if(Q[k]==1){
        for(int l=0;l<N;l++){
          if(P[l]==X+k){x=x+1;}}
        if(x==0){System.out.println(X+k);System.exit(0);}
        else{System.out.println(X-k);System.exit(0);}
      }
    }
  }
}