public static SingleNode kthToLast(SingleNode head,int k){
		SingleNode runner=head;
		for(int i=0;i<k-1;i++){
			if(runner==null) return null;
			runner=runner.next;
		}
		if(runner==null) return null;
		SingleNode nodek=head;
		while(runner.next!=null){
			nodek=nodek.next;
			runner=runner.next;
		}
		return nodek;
	}