#include<stdio.h>

int a[100010] ;

int main()
{
    int mid,beg,end,key,n,i;
    scanf("%d",&n);
    for(i=1;i<=n;i++)
    {
        scanf("%d",&a[i]);
    }
    scanf("%d",&key);
    beg=1;
    end=n;
    int res ;
    while(beg<=end)
    {
        mid= (beg+end)/2;
        if(a[mid]==key)
        {
            res = mid ;
            break;
        }
        else if(a[mid]<key)
        {
            beg=mid+1;
        }
        else if(a[mid]>key)
        {
            end=mid-1;
        }
    }
    printf("%d\n",res) ;
    return 0 ;
}