Python, модуль tkinter, конвертер валют

from tkinter import *
from tkinter import messagebox
from tkinter import ttk
import math
import sys
root = Tk()
root.title("Конвертер валют: перевод рублей в $ и евро")
bttn_list = [
"7", "8", "9","C",  "=","Exit", "+",
"4", "5", "6","-","*", "/", ".",
"1", "2", "3",
"(", ")","EUR","USD" ]
r = 1
c = 0
for i in bttn_list:
    rel = ""
    cmd=lambda x=i: calc(x)
    ttk.Button(root, text=i, command = cmd, width = 9).grid(row=r, column = c)
    c += 1
    if c > 6:
        c = 0
        r += 1
calc_entry = Entry(root, width = 33)
calc_entry.grid(row=0, column=0, columnspan=5)
#логика калькулятора
def calc(key):
    global memory
    if key == "=":
#исключение написания слов
        str1 = "-+0123456789.*/)("
        if calc_entry.get()[0] not in str1:
            calc_entry.insert(END, "First symbol is not number!")
            messagebox.showerror("Error!", "You did not enter the number!")
#исчисления
        try:
            result = eval(calc_entry.get())
            calc_entry.insert(END, "=" + str(result))
        except:
            calc_entry.insert(END, "Error!")
            messagebox.showerror("Error!", "Check the correctness of data")
        #очищение поля ввода
    elif key == "C":
        calc_entry.delete(0, END)
    elif key == "±":
        if "=" in calc_entry.get():
            calc_entry.delete(0, END)
        try:
            if calc_entry.get()[0] == "-":
                calc_entry.delete(0)
            else:
                calc_entry.insert(0, "-")
        except IndexError:
            pass
    elif key == "EUR":
        calc_entry.insert(END, "=" + str(77.04*(int(calc_entry.insert()))))
    elif key == "USD":
        calc_entry.insert(END, "=" + str(65.84*(int(calc_entry.insert()))))
        pass
 
    elif key == "Exit":
        root.after(1,root.destroy)
        sys.exit
    elif key == "(":
        calc_entry.insert(END, "(")
    elif key == ")":
        calc_entry.insert(END, ")")
    else:
        if "=" in calc_entry.get():
            calc_entry.delete(0, END)
        calc_entry.insert(END, key)
 
 
 
 
root.mainloop()

image = PhotoImage(file='wkCf6DEbLBg.gif')
logo = ttk.Label(root, image=image, compound="image")
logo.image = image
logo.pack(anchor=CENTER)

Traceback (most recent call last):
  File "C:/учеба/mdk02.01/18-19уч.год/8/Tkinter/2.4.py", line 91, in <module>
    logo.pack(anchor=CENTER)
  File "C:\Program Files\Python36\lib\tkinter\__init__.py", line 2137, in pack_configure
    + self._options(cnf, kw))
_tkinter.TclError: cannot use geometry manager pack inside . which already has slaves managed by grid
 
Process finished with exit code 1

logo.pack()