import math

from ezgraphics import GraphicsWindow

sqr = int(input("Enter square size of graphics window: "))
#sqr = 512

win = GraphicsWindow(sqr,sqr)   #create a drawing window
canvas = win.canvas()               

x_left = 1
x_right = sqr
y_down = 1
y_up = sqr

canvas.drawRectangle(0,0,sqr-1,sqr-1)
x = y = 0

for i in range(1,2*int(math.log2(sqr))):
    if i%2 == 1:
        if i%4 == 1:  #1,5,9,...
            x_left = (x_left+x_right) // 2
            canvas.setColor("black")
            canvas.drawLine(x_left,y_down, x_left,y_up)
            canvas.setColor("yellow")
            canvas.drawLine(x,y, x_left,y_up)
            x = x_left
            y = y_up
        else:         #3,7,11,...
            x_right = (x_left+x_right) // 2
            canvas.setColor("black")
            canvas.drawLine(x_right,y_down, x_right,y_up)
            canvas.setColor("yellow")
            canvas.drawLine(x,y, x_right,y_down)
            x = x_right
            y = y_down
    else:
        if i%4 == 2:  #2,6,10,...
            y_up = (y_up+y_down) // 2
            canvas.setColor("black")
            canvas.drawLine(x_left,y_up, x_right,y_up)
            canvas.setColor("yellow")
            canvas.drawLine(x,y, x_right,y_up)
            x = x_right
            y = y_up
        else:         #4,8,12,...
            y_down = (y_up+y_down) // 2
            canvas.setColor("black")
            canvas.drawLine(x_left,y_down, x_right,y_down)
            canvas.setColor("yellow")
            canvas.drawLine(x,y, x_left,y_down)
            x = x_left
            y = y_down

    #print(x_left,x_right,"  ",y_down,y_up)
print("Look at the graphics window")