Tahmid and numbers(D)

/*  TAHMID RAHMAN
    DAMIAN FOREVER
     MATH LOVER
    NEVER GIVE UP
*/
#include<bits/stdc++.h>
using namespace std;
#define pi acos(-1.0)
#define fastio ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL)
#define ll long long
#define pb push_back
#define fi first
#define se second
#define in insert
#define mp make_pair
#define GCD(a,b) __gcd(a,b);
#define endl "\n"
#define FRU freopen("out.txt","w",stdout)
#define FRO freopen("in.txt","r",stdin)
#define INFLL 9223372036854775807
#define debug 0
#define MAXN   100001
//Don't hesitate to ask me if you don't understand my code.......Happy coding,Tahmid...;
int main()
{
    fastio;
    ll n,p,i,c=INFLL,x=-1,y=0,z=0;
    cin>>n>>p;
    vector<ll>v(p);
    set<ll>s;
    if(p==0)
    {
        cout<<n<<endl;
        return 0;
    }
    for(i=0;i<p;i++)
    {
        cin>>v[i];
        if(abs(n-v[i])<c)
        {
            c=abs(n-v[i]);
            x=v[i];
        }
        s.in(v[i]);
    }
    for(i=x+1;;i++)
    {
        if(s.count(i)==0)
        {
            y=i;
            break;
        }
    }
    for(i=x-1;;i--)
    {
        if(s.count(i)==0)
        {
            z=i;
            break;
        }
    }
    if((y-x)<abs(z-x))
    {
        cout<<y<<endl;
    }
    else if(abs(z-x)<(y-x))
        cout<<z<<endl;
    else
        cout<<min(y,z)<<endl;

}