Given the head of a singly linked list and an integer n, remove the nth node from the end of the list and return the head of the modified list.

Constraints:

• The number of nodes in the list is $k$.

• $1 \leq$ $k$ $\leq 10^3$

• $−10^3 \leq$ Node.value $\leq 10^3$

• $1 \leq$ n $\leq k$