Stacks Using Linked list

This program is stacks using linked list. the program covers the following funtions:
1.Push
2.Pop
3.Display

Source Code:


class Node:
    def __init__(self,data):
        self.data=data
        self.next=None
class Stackll:
    def __init__(self):
        self.start=None
        self.top=None
    def push(self):
        data=int(input("enter data"))
        newnode=Node(data)
        if self.start==None:
           self.start=newnode
           self.top=newnode
        else:
            temp=self.start
            while temp.next!=None:
                temp=temp.next
            temp.next=newnode
            top=newnode
    def pop(self):
        temp=self.start
        if temp.next ==None:
            print ("last element of stack deleted is %d" %(temp.data))
            self.start=None
            del self.top
            self.top=None
        else:
            temp=self.start
            prev=self.start
            while temp.next != None:
                prev=temp
                temp=temp.next
         
            prev.next=None
            del temp
     
 
    def display(self):
        if self.top==None:
            print("stack empty")
        else:
            temp=self.start
            print("elements in stack are")
            while temp!=None:
                print ("%d" %(temp.data))
                temp=temp.next
             
def menu():
    print("1.push\n2.pop\n3.display\n4.quit")
def stop():
    print("you are about to terminate the program")
    exit(0)     
s=Stackll()
def default():
    print("check your input")
menu()
while True:
    menu= {
    1: s.push,
    2: s.pop,
    3: s.display,
    4: stop}
    option = int(input("Please enter your choice"))
    menu.get(option,default)()

Output:

Python 3.4.0 (v3.4.0:04f714765c13, Mar 16 2014, 19:24:06) [MSC v.1600 32 bit (Intel)] on win32
Type "copyright", "credits" or "license()" for more information.
>>> ================================ RESTART ================================
>>>
1.push
2.pop
3.display
4.quit
Please enter your choice1
enter data10
Please enter your choice1
enter data20
Please enter your choice1
enter data30
Please enter your choice3
elements in stack are
10
20
30
Please enter your choice2
Please enter your choice3
elements in stack are
10
20
Please enter your choice2
Please enter your choice3
elements in stack are
10
Please enter your choice2
last element of stack deleted is 10
Please enter your choice3
stack empty

Please enter your choice4

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