画国际象棋盘

#画国际象棋盘，小格边长为width
import turtle
turtle.speed(0)
width = eval(input())

#画黑格
def drawSquare(width):
    turtle.pendown()
    turtle.begin_fill()
    turtle.fillcolor("black")
    for i in range(4):
        turtle.forward(width)
        turtle.left(90)
    turtle.end_fill()
    turtle.penup()

for i in range(8):
    if i % 2 == 0:#偶数行
        turtle.penup()
        turtle.goto(0, i * width)
        turtle.pendown()
        for j in range(4):
            drawSquare(width)
            turtle.fd(2 * width)
    else:
        turtle.penup()
        turtle.goto(width, i * width)
        turtle.pendown()
        for j in range(4):
            drawSquare(width)
            turtle.fd(2 * width)
turtle.penup()
turtle.goto(0,0)
turtle.pendown()
for i in range(4):
    turtle.forward(8 * width)
    turtle.left(90)
turtle.hideturtle()
turtle.done()