a=[1,2,9]
b=[4,5]


def middle(a,b):
c=a+b
c.sort()
if len(c)%2==1:
return c[int(len(c)/2)]
else:
return 0.5*( c[int(len(c)/2)-1]+ c[int(len(c)/2)])

print(middle(a,b))