'''
by Ching-Shoei Chiang
'''
import pygame, sys
from pygame.locals import *

#          (R,G,B)
BLACK    = (0,0,0)          # Three 0
RED      = (255,0,0)        # Two 0
GREEN    = (0,255,0)
BLUE     = (0,0,255)
CYAN     = (0,255,255)      # One 0
MAGENTA  = (255,0,255)
YELLOW   = (255,255,0)
WHITE    = (255, 255, 255)  # Three 255

pygame.init()
screen = pygame.display.set_mode((800, 800))
pygame.display.set_caption("Professor Chiang's Game")

dir = 1
y = 200
screen.fill(WHITE)

# Setting the main program loop
while True:
    # Main event loop
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            pygame.quit()
            sys.exit()

    y = y + dir
    if y > 600 or y < 200:
        dir = -1 * dir

# draw rectangle


    pygame.draw.circle(screen, CYAN, (600,y),200,0)
    pygame.display.clear()
    pygame.display.update()