import pygame

WIDTH = 800
HEIGHT= 600
SIZE = (WIDTH, HEIGHT)
RED = (255, 0, 0)
CIRCLE_RADIUS = 10
BLACK = (0, 0, 0)
FPS = 120

def main():
    screen = init_game()
    game_loop(screen)
    exit_game()

def init_game():
    global position
    global clock
    clock = pygame.time.Clock()
    position = (WIDTH // 2, HEIGHT // 2)
    pygame.init()
    return pygame.display.set_mode(SIZE)

def game_loop(screen):
    while True:
        if not event_handling():
            break
        if not update_game():
            break
        event = event_handling()
        draw_game(screen)
        clock.tick(FPS)

def event_handling():
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            return False
    return True

def update_game():
    global position
    keys_pressed = pygame.key.get_pressed()
    if keys_pressed[pygame.K_UP]:
        position = (position[0], position[1] - 1)
    if keys_pressed[pygame.K_DOWN]:
        position = (position[0], position[1] + 1)
    if keys_pressed[pygame.K_LEFT]:
        position = (position[0] - 1, position[1])
    if keys_pressed[pygame.K_RIGHT]:
        position = (position[0] + 1, position[1])
    return True

def draw_game(screen):
    screen.fill(BLACK)
    pygame.draw.circle(screen, RED, position, CIRCLE_RADIUS)
    pygame.display.flip()

def exit_game():
    pygame.quit()

main()