#include<stdio.h>
int main()
{
    int n;
    scanf("%d",&n);
    int a[n];
    for(int i=0;i<n;i++)
    {
        scanf("%d",&a[i]);
    }
    int x;
    scanf("%d",&x);
    binary_search(a,n,x);
}
int binary_search(int a[],int n,int x)
{
    int s=0;
    int e=n-1;
    while(s<n)
    {
        int mid=(s+e)/2;
        if(a[mid]==x)
        {
            return i;
        }
        else if(a[mid]<x)
        {
            s=mid+1;
        }
        else
        {
            e=mid-1;
        }
    }
}