from turtle import *
from random import *
t=pen()
title("Вкладені квадрати ")  
setup(400,400)
reset()
bgcolor('green');
pensize(4)
color('yellow')
for r in range(200,1,-10):
  up()
  goto(-r//2,r//2)
  down()
  for k in range(4):
       forward(r)
       right(90)
pensize(6)
color('green')
for r in range(1,210,10):
  up()
  goto(-r//2,r//2)
  down()
  for k in range(4):
       forward(r)
       right(90)
exitonclick()