Calculating with float

[TSheets13]

This code fails:

import math
r=input("r=")
h=input("h=")
V=math.pi*h*r**2
print (V)

V=math.pi*h*r**2
TypeError: can't multiply sequence by non-int of type 'float'


While this works:

import math
r=3.5
h=9
V=math.pi*h*r**2
print (V)

Can someone tell me where the difference lies and how to make the first bit of code work?

Thanks