#include<stdio.h>
#include<stdlib.h>

int main()
{
    int i,j,k,l=0,n,target,term;
    int arr[100],num1[100];
    scanf("%d",&n);
    for(i=1;i<=n;i++)
    {
        scanf("%d",&arr[i]);
    }
    scanf("%d",&target);
    int hi,low,mid;
    low=1;
    hi=n;
    for(i=1;i<n;i++)
    {
        for(j=i+1;j<=n;j++)
        {
            if(arr[i]<arr[j])
            {
                term=arr[i];
                arr[i]=arr[j];
                arr[j]=term;

            }
        }
    }

    while(l==0)
    {
        mid=(hi+low)/2;
        if(arr[mid]>target)
        {
            low=mid+1;
            printf("arr[mid]=%d\n",arr[mid]);
        }
        else if(arr[mid]<target)
        {
            hi=mid-1;
            printf("arr1[mid]=%d\n",arr[mid]);
        }
        else if(arr[mid]==target)
        {
            printf("YES");
            l=1;

        }
        if(low>hi)
        {
            printf("NO");
            l=1;
        }
    }


}