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)

/****************************************************************************************************
                                        SUBMITTED BY-

                                                AISH_07

****************************************************************************************************/
#include<bits/stdc++.h>
using namespace std;
#define vi vector<int>
#define ll long long
#define sl set<ll>
#define vs vector<string>
#define vl vector<ll>
#define vi vector<int>
#define pb push_back
#define PI  3.14159265
#define mod 1000000007
int main()
{
    int x,n;
    cin>>x>>n;
    vi a;


    for(int i=0;i<n;i++)
    {
        int k;
        cin>>k;
        a.pb(k);
    }
    sort(a.begin(),a.end());

    if(n==0)
        cout<<x<<"\n";
    else if(n==1)
    {
        if(a[0]==1)
            cout<<"2\n";
        else if(a[0]==0)
            cout<<"1\n";
        else
            cout<<a[0]-1<<"\n";
    }
    else
    {
    if(!binary_search(a.begin(),a.end(),x))
        cout<<x<<"\n";
    else
    {
        int p=a[n-1];
        int num=101,num2=0;
        for(int i=x+1;i<=p+1;i++)
        {
            if(!binary_search(a.begin(),a.end(),i))
            {
                num=i;
                break;
            }
        }
        for(int i=x-1;i>=0;i--)
        {
            if(!binary_search(a.begin(),a.end(),i))
              {
               num2=i;
                break;
              }
        }
        int s=x-num2;
        int t=num-x;
        if(s<=t)
            cout<<num2<<"\n";
        else
          cout<<num<<"\n";

    }
    }

    return 0;
}