编写程序，建立2个带头结点单链表，输入若干整数将正整数插入第1个单链表，将负整数插入第2个单链表，插入前和插入后单链表保持递增或相等次序，显示2个单链表，最后销毁。程序不可存在内存泄漏。

class Node:
    def __init__(self, data=None, next=None):
        self.data = data
        self.next = next

class LinkedList:
    def __init__(self):
        self.head = Node()

    def insert(self, data):
        new_node = Node(data)
        current = self.head

        while current.next and current.next.data < data:
            current = current.next

        new_node.next = current.next
        current.next = new_node

    def display(self):
        current = self.head.next

        while current:
            print(current.data, end=' ')
            current = current.next

        print()

    def destroy(self):
        current = self.head

        while current:
            temp = current.next
            del current
            current = temp

def main():
    list1 = LinkedList()
    list2 = LinkedList()

    while True:
        try:
            data = int(input())
        except:
            break

        if data > 0:
            list1.insert(data)
        else:
            list2.insert(data)

    list1.display()
    list2.display()

    list1.destroy()
    list2.destroy()

if __name__ == '__main__':
    main()

输入样例：

1
2
-1
-2
3
-3
0

输出样例：

1 2 3 
-3 -2 -1