$7.$ Given the head of a linked list, remove the nth node from the end of the list and return its head.

In the following code, we are given the head of a linked list. What is the missing piece of code needed to remove the nth node from the end of the list and return its head?

$/**$

$*$ Definition for singly$-$linked list.

$*$ public class ListNode $\{$

$*$ int val;

ListNode next;

$*$ ListNode $)(\}$

$*$ ListNode $($int val$)\{$ this.val $=$ val; $\}$

$*$ ListNode$($int val, ListNode next$)\{$ this.val $=$ val; this.next $=$ next; $\}$

$*$

$*/$

class Solution $\{$

public ListNode removeNthFromEnd $($ListNode head, int n$)$ f

int count $=1$;

ListNode c $=$ head;

while $($c$.$next! $=$null$)\{$

count$++$;

c$=$c$.$ next;

if$($n $==$ count$)\{$

head $=$ head.next;

return head;

$$

ListNode In $=$ head;

int i$=0$;

while $(++$i