/**
knakul853
 */
class Solution {
public:
    ListNode* removeNthFromEnd(ListNode* head, int n) {


        int len = 0;
        ListNode* cur = head;

        while(cur){
            cur = cur->next;
            len++;
        }

        if( n > len) return NULL;

        if(len == n )
        {
            return head->next;
        }
        n = len - n;
        n--;
        cur = head;
        while(cur && n>0)
        {
            cur = cur->next;
            n--;
        }
           cur->next = cur->next->next;
        return head;



    }
};