Как активировать кнопку после проверки введенного числа в окно?

import tkinter as tk                # python 3
from tkinter import font  as tkfont # python 3
#import Tkinter as tk     # python 2
#import tkFont as tkfont  # python 2
 
class SampleApp(tk.Tk):
 
    def __init__(self, *args, **kwargs):
        tk.Tk.__init__(self, *args, **kwargs)
        self.title_font = tkfont.Font(family='Helvetica', size=18, weight="bold", slant="italic")
        # the container is where we'll stack a bunch of frames
        # on top of each other, then the one we want visible
        # will be raised above the others
        container = tk.Frame(self)
        container.pack(side="top", fill="both", expand=True)
        container.grid_rowconfigure(0, weight=1)
        container.grid_columnconfigure(0, weight=1)
 
        self.frames = {}
        for F in (StartPage, PageOne, PageTwo, PageThree):
            page_name = F.__name__
            frame = F(parent=container, controller=self)
            self.frames[page_name] = frame
 
            # put all of the pages in the same location;
            # the one on the top of the stacking order
            # will be the one that is visible.
            frame.grid(row=0, column=0, sticky="nsew")
 
        self.show_frame("StartPage")
 
    def show_frame(self, page_name):
        '''Show a frame for the given page name'''
        frame = self.frames[page_name]
        frame.tkraise()
 
 
class StartPage(tk.Frame):
 
    def __init__(self, parent, controller):
        tk.Frame.__init__(self, parent)
        self.controller = controller
        label = tk.Label(self, text="This is the start page", font=controller.title_font)
        label.pack(side="top", fill="x", pady=10)
 
        button1 = tk.Button(self, text="Go to Page One",
                            command=lambda: controller.show_frame("PageOne"))
        button2 = tk.Button(self, text="Go to Page Two",
                            command=lambda: controller.show_frame("PageTwo"))
       # button3 = tk.Button(self, text="Go to Page Three",
                            #command=lambda: controller.show_frame("PageThree"))
        button1.pack()
        button2.pack()
        #button3.pack()
 
 
class PageOne(tk.Frame):
    
    def __init__(self, parent, controller):
        password = tk.IntVar()
        p = password.get()
        
        tk.Frame.__init__(self, parent)
        self.controller = controller
        ent = tk.Entry(self, width=10,bd=3, textvariable=password)
        
        label = tk.Label(self, text="This is page 1", font=controller.title_font, textvariable=password)
        #label.pack(side="top", fill="x", pady=10)
        #password=input()
        #if (password.get=="2517"):
        submit = tk.Button(self, text='Далее',
                           command=lambda: controller.show_frame("PageThree"))
        #else:
            #print ("yes")
        
        button = tk.Button(self, text="Go to the start page",
                           command=lambda: controller.show_frame("StartPage"))
        ent.pack()
        submit.pack()
        label.pack()
        button.pack()
 
 
class PageTwo(tk.Frame):
 
    def __init__(self, parent, controller):
        tk.Frame.__init__(self, parent)
        self.controller = controller
        label = tk.Label(self, text="This is page 2", font=controller.title_font)
        label.pack(side="top", fill="x", pady=10)
        button = tk.Button(self, text="Go to the start page",
                           command=lambda: controller.show_frame("StartPage"))
        button.pack()
 
class PageThree(tk.Frame):
 
    def __init__(self, parent, controller):
        tk.Frame.__init__(self, parent)
        self.controller = controller
        labe3 = tk.Label(self, text="This is page 3", font=controller.title_font)
        labe3.pack(side="top", fill="x", pady=10)
        button = tk.Button(self, text="Go to the start page",
                           command=lambda: controller.show_frame("StartPage"))
        button.pack()
 
 
if __name__ == "__main__":
    app = SampleApp()
    app.mainloop()