import pygame
import random
import sys
 
FPS = 60
W = 500
H = 500 
WHITE = (255, 255, 255)

 
sc = pygame.display.set_mode((W, H))
clock = pygame.time.Clock()

x = 0
y = 0

sc.fill((200, 255, 200))

while 1:
    for i in pygame.event.get():
        if i.type == pygame.QUIT:
            sys.exit()
    
    pygame.draw.rect(sc, WHITE , (x, y+10, 10, 10))
    pygame.draw.rect(sc, WHITE , (y+20, x, 10, 10))
    x = x + 10
    if x > 400:
     y = y + 20
     x = 0

    pygame.display.update()
    clock.tick(FPS)