CountDown Time using Tkinter

import time # initialize time library

from tkinter import * # initialize all from tkinter library

from tkinter import messagebox # initialize messagebox from tkinter library

# creating Tk window #root is the variable

root = Tk() # root is the variable

# setting geometry of tk window

root.geometry("260x120") # size of window

root.title("Time Counter") # Title heading

root.configure(bg='#856ff8') # color #856ff8

# Declaration of variables

hour=StringVar()

minute=StringVar()

second=StringVar()

# setting the default value as 0

hour.set("00")

minute.set("00")

second.set("00")

# Use of Entry class to take input from the user

hourEntry= Entry(root, width=3, font=("Arial",18,""),

                textvariable=hour,foreground='white',background='blue')

hourEntry.place(x=60,y=20)

minuteEntry= Entry(root, width=3, font=("Arial",18,""),

                textvariable=minute,foreground='white',background='blue')

minuteEntry.place(x=110,y=20)

secondEntry= Entry(root, width=3, font=("Arial",18,"" ),

                textvariable=second,foreground='white',background='blue')

secondEntry.place(x=160,y=20)

def submit(): # function

    try:

        t = int(hour.get())*3600 + int(minute.get())*60 + int(second.get())

    except:

        print("Please input the right value")

    while t >-1:

        

        mins,secs = divmod(t,60)

        hours=0

        if mins >60:

            

        

            hours, mins = divmod(mins, 60)

        hour.set("{0:2d}".format(hours)) # hours

        minute.set("{0:2d}".format(mins)) # minutes

        second.set("{0:2d}".format(secs)) # sec

        root.update()

        time.sleep(1)

        if (t == 0): # if time ==0 display message

            messagebox.showinfo("Time Countdown", "Time's up ")

        

        t -= 1 # decrease the count

btn = Button(root, text='Set Time Countdown', bd='5',foreground='white',background='blue',

            command= submit)

btn.place(x = 65,y = 70)

root.mainloop()