#include <iostream>
#include <fstream>
#define nmax 100005
using namespace std;
int v[nmax],n,x,r;

int main()
{
    ifstream f("main.in");
    ofstream g("main.out");

    int i,j;
    f>>n;
    for (i=1;i<=n;i++)
            f>>v[i];
    f>>x;
    i=1;
    j=n;
    while (1)
    {
        r=(i+j)/2;
        if (x<v[r])
        {
            j=r-1;
        }
        else if (x>v[r])
        {
            i=r+1;
        }
        else if (v[r]==x) {g<<r; break;}
    }
}