bainary such

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
#define fastread() (ios_base:: sync_with_stdio(false),cin.tie(NULL))
#define fi first
#define se second
#define pb push_back
#define eb emplace_back
void input(ll ara[],ll n)
{
    for(ll i=0; i<n; i++)
        cin>>ara[i];
}

#define eb emplace_back
int main()
{
    fastread();



    ll n;

    cin>>n;

    ll ara[n+1];

    input(ara,n);

    sort(ara,ara+n);
    ll s=0,e=n-1;
    ll mid=(s+e)/2;

    ll key;
    bool f=false;
    cin>>key;


    while(s<=e)
    {

      cout<<mid<<endl;
        if(ara[mid]==key)
        {
            f=true;
            break;
        }
        else if(ara[mid]>key)
        {
            e=mid-1;

        }
     else if(ara[mid]<key)
        {
            s=mid+1;
        }
        mid=(s+e)/2;


    }
    if(f==true)cout<<"YES"<<endl;
    else cout<<"NO"<<endl;
















    }