import pygame
import random

WIDTH = 500
HEIGHT = 700
FPS = 60

WHITE = (255, 255, 255)
BLACK = (0, 0, 0)
RED = (255, 0, 0)
GREEN = (0, 255, 0)
BLUE = (0, 0, 255)

pygame.init()
screen = pygame.display.set_mode((WIDTH, HEIGHT))
f1 = pygame.font.Font(None, 36)
running = True

x = 0
y = 0

while running:
    
    for event in pygame.event.get():
        
     if event.type == pygame.QUIT:
            running = False

    for it_1 in range(0,500,50):
       for it_2 in range(0,500,50):
        pygame.draw.rect(screen,WHITE, (it_1,it_2,49,49))
    if (x < 0): x = 0
    if (x > 450): x = 450
    if (y > 500): y = 500
    if (y < 100): y = 100

    direction = random.randint(0,4)
    if (direction == 0): 
     x = x + 50
    if (direction == 1): 
     x = x - 50
    if (direction == 2):
     y = y + 50
    if (direction == 3):
     y = y - 50
 
    pygame.draw.rect(screen,GREEN, (x,y,49,49))
    
    pygame.display.update()
    pygame.time.delay(250) 
pygame.quit()