import pygame as p,random
q=p.display
T=16
b=q.set_mode([256]*2).fill
l=[]
d=a=x=1
c=p.event.get
while not(x&528or x in l):
l=l[a!=x:]+[x]
while a&528or a in l:a=random.randrange(512)
b(0);[b(99,(o%T*T,o/32*T,T,T))for o in l+[a]];q.flip();p.time.wait(99);D=d
for e in c(2):
v=e.key-272;n=((v&2)-1)*[1,32][v<3]
if-n-D and 0<v<5:d=n
c();x+=d