import java.util.*;
public class Main {
public static void main(String args[]) {
int[] arra = takeInput();
System.out.println(Binary_Search(arra, 0, arra.length-1, 6));
}
public static int Binary_Search(int[] arr, int lo, int hi, int ele) {
int mid = (lo + hi) / 2;
if(lo>hi) {
return -1;
}
while (lo <= hi) {
if (ele < arr[mid]) {
hi = mid-1;
} else if (ele == arr[mid]) {
// System.out.println(mid);
break;
} else {
lo = mid+1;
}
mid = (lo + hi) / 2;
}
return mid;
}
public static int[] takeInput() {
Scanner scn = new Scanner(System.in);
int n = scn.nextInt();
int[] arr = new int[n];
for(int i=0; i<n; i++) {
arr[i] = scn.nextInt();
}
return arr;
}
}