from turtle import *

shape('turtle')
setup(450, 450)
speed(0), hideturtle()

def p(x, y):
    penup(), setpos(x, y)
    pendown(), seth(0)

def kv(x1, y1, x2, y2, c = ""):
    p(x1, y1)
    d = abs(x2 - x1)
    color("black", c)
    begin_fill()
    for _ in range(4):
        fd(d), rt(90)
    end_fill()


a = int(input("введи а = "))
x1 = -200; y1 = 200
x2 = 200; y2 = -200
for _ in range(20): 
    kv(x1, y1, x2, y2)
    x1 += a; y1 -= a
    x2 -= a; y2 += a

done()