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: Accepted)

#include<bits/stdc++.h>
using namespace std;
int main()
{
    int x,n,arr[105];
    cin>>x>>n;
    for(int i=0; i<n; i++)
    {
        cin>>arr[i];
    }

    int ans=0,flag=0;
    int k=0,a=0,b=0;
    while(flag==0)
    {
        a=x+k;
        b=x-k;
        int d=0,e=0;
        for(int i=0;i<n;i++)
        {
            if(a==b)
            {
                if(arr[i]==a)
                {
                    d=1;
                    e=1;
                }
            }
            else if(arr[i]==a)
            {
                d=1;
            }
            else if(arr[i]==b)
            {
                e=1;
            }
        }
        if(d==0&&e==0)
        {
            ans=min(a,b);
            flag=1;
        }
        else if(d==0)
        {
            ans=a;
            flag=1;
        }
        else if(e==0)
        {
            ans=b;
            flag=1;
        }
        k++;
    }
    cout<<ans<<endl;
    return 0;
}