Program crash when executing the function. Tkinter + Python3

This is the following I created a simple program to break numeric md5, but the same hangs when I click on descrypter and it only works again when it finds the hash, but it gets stuck until it finds and has hash like hash md5 of '81748856' which takes 5 minutes, and it gets stuck all the time has how do it not lock and execute function?

from tkinter import *
root=Tk()
def decripter():
    from hashlib import md5
    import time
    a=str(h.get()).strip()
    if len(a)==32 and a.isdigit()==False and a.isalpha()==False and a.isalnum()==True:
        pass
    elif len(a) <32:
        lab1["text"]=f"\n\nTá faltando {32 - len(a)} caracteres!"
        lab1["font"]="Arial 9 bold"
        return
    else:
        lab1["text"]="\n\nTem certeza que isso é um MD5(number)?"
        lab1["font"]="Arial 9 bold"
        return
    inicio = time.time()
    n=0
    while(True):
        d= md5(str(n).encode()).hexdigest()
        if int((time.time()-inicio)) > 300:
            lab1["text"]=f"\nO tempo limite de {int(time.time()-inicio)}s se esgotou, a string não foi detectada!"
            lab1["font"]="Arial 9 bold"
            return
        if d==a:
            lab1["text"]=f"\nProcurando isso? '{n}'"
            lab1["font"]="Arial 11 bold"
            break
        else:
            n+=1

root.geometry("500x180")

root.title("Decry(MD5(num)) v1.0")

lab=Label(root, font="Arial 9 bold" , text="Bem vindo ao Decry(MD5(num)) na atual versão '1.0' \nO proposito principal desse programa é 'Descriptografar' hash Md5(number)\n\n").pack()


h=Entry(root, width=40,font="Arial 12 bold")
h.pack()
Button(root, text='Decrypter', command=decrypter).pack()
lab1=Label(root, font="Arial 9 bold" , text="\n\nTodos os direitos reservados a Code Ghost.")
lab1.pack()
root.mainloop()