g = 9.8
h = input("the height h(meter) of the tower :")
t = input("the time intrval t(second) :")
s= 1.0/2.0 * g * t ** 2
H= h - 1.0/2.0 * g * t ** 2    #the height above the ground
print "the height of the ball above the groud after time interval is",H,"meters"





