package main

type ListNode struct {
     Val int
     Next *ListNode
}

func partition(head *ListNode, x int)  *ListNode {
	if head == nil {
		return nil
	}
	stack1 , stack2 := &ListNode{0,nil} , &ListNode{0,nil}
	l1 , l2 := stack1 , stack2
	for head != nil {
         if head.Val >= x {
         	stack2.Next = &ListNode{head.Val,nil}
         	stack2 = stack2.Next
         }else {
			 stack1.Next = &ListNode{head.Val,nil}
			 stack1 = stack1.Next
		 }
		 head = head.Next
    }
	if l1.Next == nil {
		return l2.Next
	}
	l1 = l1.Next
	stack1.Next = l2.Next
    return l1
}