I cant't generate a random number and print it

I can't generate the number because I get the error NameError: name 'z' is not defined.

import tkinter as tk
from random import randint

def randomize():
    z.set ( randint(x.get(),y.get()))

root = tk.Tk()

x = tk.IntVar()
y = tk.IntVar()

text= tk.Label(root, text = "press the button for random number")
enterX = tk.Entry(root)
enterY = tk.Entry(root)
button = tk.Button(root, text = "Press here", command=randomize)
result = tk.Label(root,text="Number is:")
number = tk.Label(root, textvariable=z)

text.pack()
enterX.pack()
enterY.pack()
button.pack()
result.pack()
number.pack()

root.mainloop()

I need help to resolve the error