Квадратик не прыгает и не двигается вверх и вниз. Кто может разобраться?

import pygame

pygame.init()
win = pygame.display.set_mode((500, 500))

pygame.display.set_caption("Cubes Game")

x = 50
y = 475
width = 20
height = 20
speed = 15
isjump = True
jumpCount = 10
run = True
while run:
    pygame.time.delay(25)

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

    keys = pygame.key.get_pressed()
    if keys[pygame.K_LEFT] and x > 5:
        x -= speed
    if keys[pygame.K_RIGHT] and x < 495 - width - 5:
        x += speed
    if not(isjump):
        if keys[pygame.K_UP]and y > 5:
            y -= speed
        if keys[pygame.K_DOWN] and y < 495 - height - 5:
            y += speed
        if keys[pygame.K_SPACE]:
            isJump = True
        else:
            if jumpCount >= -10:
                if jumpcount < 0:
                    y += (jumpCount ** 2) / 2
                else:
                    y -= (jumpCount ** 2) / 2
                jumpCount -= 1
            else:
                isJump = False
                jumpCount = 10

    win.fill((0,0,0))
    pygame.draw.rect(win, (0,0,255), (x, y, width, height))
    pygame.display.update()


pygame.quit()