import random
import time
width=50
mid = 1
pline = ""
s = " "
change = 0;
i=0
while 1:
        i+=1
        ran = random.randint(0,1)
        if ran == 0: mid += -2
        else : mid += 2
        if i%10==0 : change += random.randint(-1,1)
        if mid > width-4 : mid = width-4
        if mid <= 0 : mid = 0
        side = (width-mid)/2
        pline = s*(side+change)
        pline += "*"*mid
        pline +=s*(side-change)
        print pline
        time.sleep(.02)