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)

//Author- VMAX


#include<bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
#define ordered_multiset tree<long long , null_type,less_equal<long long >, rb_tree_tag,tree_order_statistics_node_update>
#define ordered_set tree<long long , null_type,less<long long >, rb_tree_tag,tree_order_statistics_node_update>
using namespace std;
#define ll long long int
#define YES cout<<"YES"<<"\n";
#define NO cout<<"NO"<<"\n";
#define ld     long double 
#define yes cout<<"yes"<<"\n";
#define no cout<<"no"<<"\n";
#define No cout<<"No"<<"\n";
#define Yes cout<<"Yes"<<"\n";
#define f(i,a) for(i=0;i<a;i++)
#define fo(i,a) for(i=1;i<=a;i++)
#define fa(i,a) for(auto i:a)
#define r(i,a) for(auto i=a.rbegin();i!=a.rend();i++)
#define en cout<<"\n";
#define ull unsigned long long int
#define o(x) cout<<x<<"\n";
#define o1(x) cout<<x<<" ";
#define pb push_back
#define F first
#define in insert
#define mp make_pair
#define S second
#define pre(n) cout<<fixed<<setprecision(n);
#define      gcd(a,b)    __gcd(a,b)
#define bs            binary_search
#define fast ios_base::sync_with_stdio(false);cin.tie(NULL);
#define test ll t;cin>>t;while(t-->0)
const ll Mod = 998244353;
#define mod 1000000007
#define pi 3.14159265358979323846
#define all(x) x.begin(),x.end()
#define re return 0;
// *#######################################################################################*
/*
ll prf(ll n)
{
    ll c=0,i;
    while(n%2==0)
    {
        n=n/2;
        c++;
    }
    for(i=3;i*i<=n;i++)
    {
        while(n%i==0)
    }
    
    
    
}
*/
//vector<ll>a(26);
int main()
{
     
      
      ll x,n;
      cin>>x>>n;
      ll i,y;
      
      set<ll>s;
      
      f(i,105)
      {
          s.in(i);
      }
      /*
      fa(i,s)
      {
          o1(i)
      }
      */
      
      f(i,n)
      {
          cin>>y;
          s.erase(y);
      }
      
      ll mn=1e18,p=x;
      fa(i,s)
      { ll zz=abs(x-i);
          if(zz<mn)
          {
              mn=zz;
              p=i;
          }
          
      }
      
      //o(x)
      o(p)
      
      
     

      
  
     re
}