#include
using namespace std;
int find_index(int n,int a[], int key)
{
int start=0;
int end=n-1;
while(start<=end)
{
int mid=(start+end)/2;
if(a[mid]==key)
return mid;
if(a[mid]<a[start])
{
if(key>a[mid] and key<a[end])
start=mid+1;
else
end=mid-1;
}
if(a[mid]>a[end])
{
if(key>a[start] and key<a[mid])
end=mid-1;
else
start=mid+1;
}
}
return -1;
}
int main()
{
int n;
cin>>n;
int a[n];
for( int i=0;i<n;i++)
cin>>a[i];
int key;
cin>>key;
cout<<find_index(n,a,key)<<endl;
}