text: import math
  import time
  from tkinter import *
  from math import*
  
  def submit():
      try:
          value = int(entry.get())
          print("value is: " + str(value)) #debug
          calcolaF(value)
      except:
          pass
  
  def calcolaF(value):
      oldValue=value
      label_2["text"] = f"Il fattoriale di {oldValue} è {math.factorial(value)}"
      label_2.grid(row=2, column=0)
  
  w = Tk()
  w.geometry("800x800")
  w.title("Fattoriale di Dom")
  #icon = PhotoImage(file="img.png")
  #w.iconphoto(True,icon)
  w.config(background="lightgrey")
  w.grid_columnconfigure((3,1),weight=2)
  
  label = Label(w,
                text="Inserisci il fattoriale:",
                font=("Arial",30,'bold'),
                fg="green",
                bg="lightgrey",
                bd=10,
                padx=20,
                pady=20,
                compound='left',
                height=1,
                )
  crediti = Label(w,
                  text="Author = Luca Ghirimoldi",
                  font=('Arial',20,'bold'),
                  bg="blue",
                  fg="lightblue",
                  padx=10,
                  pady=10
                  )
  button = Button(w,
                  text="Calcola",
                  bg="lime",
                  fg="darkgreen",
                  activebackground="green",
                  activeforeground="lime",
                  font=("Arial",25,'bold'),
                  padx=20,
                  pady=12,
                  command=submit)
  label_2 = Message(w,
                  text="",
                  fg="green",
                  bg="lime",
                  padx=13,
                  pady=13,
                  bd=10,
                  font=("Arial",25,'bold')
                  )
  entry = Entry(w,
                bg="lime",
                font=("Arial",19,"bold"),
                fg="darkgreen"
                )
  
  label.grid(row=1,column=0)
  entry.grid(row=1,column=1)
  button.grid(row=2,column=1)
  crediti.grid(row=3,column=0)
  
  w.mainloop()