#include #include using namespace std; int arr[1000005], n, k; int main() { scanf("%d", &n); for (int i = 1; i <= n; i++) scanf("%d", &arr[i]); scanf("%d", &k); int left = 1, right = n, mid; while (left <= right) { mid = (left + right) / 2; if (k == arr[mid]) { cout << mid; return 0;

	}

	if (k <= arr[mid])
		left = mid + 1;
	if (k >= arr[mid])
		right = mid - 1;
}

cout<<-1;

}