Check if the node has a right sibling and it has $<2<2$d keys. If so$,$ shift the rightmost key up to the parent node and the key from the parent node as the leftmost key of the right sibling. If the node$/$right sibling is not a leaf, we need to move pointers as well.

Check if the node has a left sibling and it has $<2<2$d keys. If so$,$ shift the leftmost key up to the parent node and the key from the parent node as the rightmost key of the left sibling. If the node$/$left sibling is not a leaf, we need to move pointers as well.

If both of the conditions above do not hold, split the node into two according to the median and insert a parent at the leaf. This is the same procedure as before.

The advantages of d