pygame.key.set_repeat(1, 1)

while True:

    # user hasn't moved anything yet
    dx, dy = 0, 0

    for event in pygame.event.get():
        if (event.type == QUIT) or (event.type == KEYDOWN and event.key == K_ESCAPE):
            sys.exit(0)

        elif event.type == KEYDOWN:
            pressedkeys = pygame.key.get_pressed()
            if pressedkeys[K_UP] or pressedkeys[K_w]:
                dy -= 1
            if pressedkeys[K_DOWN] or pressedkeys[K_s]:
                dy += 1
            if pressedkeys[K_LEFT] or pressedkeys[K_a]:
                dx -= 1
            if pressedkeys[K_RIGHT] or pressedkeys[K_d]:
                dx += 1

    if dy!=0 or dx!=0:
        p1.move((0, dy))
        p2.move((dx, 0))
        p3.move((0, dy))