Why Did the Cow Cross the Road 12

This time we found John's farm without trouble, but the plan still fell through for a different reason: someone found an error in his theory of cow friendliness.

John's farm has $N$ breeds of cows, numbered $1, 2, \ldots, N$. Cows of breed $a$ and breed $b$ are friendly if $|a-b| \le K$, and unfriendly otherwise. Pastures for different breeds are built so differently that each pasture can hold only one specific breed: pasture $i$ can graze only cows of breed $i$. When a cow crosses the road, it walks to the pasture on the other side that grazes its own breed.

For the new members of the Help John Association, here is the farm layout again. The farm has one straight road with $N$ pastures on each side. On the left side, each breed occupies exactly one pasture, and the same holds on the right side. John paid no attention to the order when he built the pastures, so the paths of a breed $a$ cow and a breed $b$ cow may cross each other. Call such a pair of breeds $(a, b)$ a "crossing pair".

Before installing crosswalks, we want to count the crossing pairs whose breeds are unfriendly. The term of the association's president is almost over, so this is our last task. Let's help John one last time.

The first line contains $N$ ($1 \le N \le 100{,}000$) and $K$ ($0 \le K < N$). Each of the next $N$ lines contains one pasture number, listing the pastures on the left side of the road in order. Every breed appears exactly once. The next $N$ lines list the pastures on the right side of the road in the same format.

Print the number of crossing pairs whose breeds are unfriendly.

In the first example, breeds $1$ and $4$, and breeds $1$ and $3$, are the crossing pairs that are unfriendly.