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 C++ (GCC 9.2.1) (judge verdict: Wrong Answer)

#include<bits/stdc++.h>
using namespace std;
int main()
{
    int x,n;
    cin>>x>>n;
    int a[n];
    int b[102]={0};
    for(int i=0;i<n;i++)
    {
        cin>>a[i];
        b[a[i]]++;
    }
    if(n==0)
        cout<<x<<endl;
    else
    {
        int pr=x-1;
        int aag=x+1;
        while(1)
        {
            if(b[pr]!=0 && b[aag]==0)
            {
                cout<<aag<<endl;
                break;
            }
            else if(b[pr]==0 && b[aag]!=0)
            {
                cout<<pr<<endl;
                break;
            }
            else if((b[pr]==1 && b[aag]==1) &&(pr>=0 && aag<=102))
            {
                pr--;
                aag++;
            }
            else if(b[pr]==0 && b[aag]==0)
            {
                cout<<pr<<endl;
                break;
            }
        }
        }
    return 0;
}