class Solution(object):

    def removeElements(self, head, val):

        """

        :type head: ListNode

        :type val: int

        :rtype: ListNode

        """

        pre = ListNode(0)

        pre.next = head

        while pre.next!=None:

            if pre.next.val == val:

                if pre.next == head:

                    head = head.next

                    pre.next = pre.next.next

                else:

                    pre.next = pre.next.next

            else:

                pre = pre.next

        return head