#include<bits/stdc++.h> using namespace std; const int N=10010; int a[N],n,x; int search(int l,int r,int x){ while(l<=r){ int mid=(l+r)>>1; if(a[mid]==x) return mid; else if(a[mid]>x) r=mid-1; else l=mid+1; } return -1; } int main(){ cin>>n; for(int i=1;i<=n;i++){ cin>>a[i]; } cin>>x; cout<<search(1,n,x); }