/*
struct ListNode {
	int val;
	struct ListNode *next;
	ListNode(int x) :
			val(x), next(NULL) {
	}
};*/
class Solution {
public:
    ListNode* FindKthToTail(ListNode* head, unsigned int k) {
		if (k < 0) return nullptr;
		ListNode* temp = head;
		while (k -- && temp) temp = temp->next;
		if (k != -1) return nullptr;
		while (temp) {
			temp = temp->next;
			head = head->next;
		}
		return head;
    }
};