Math operation cilinder python

import math
r = float(input('Enter r: '))
h = float(input('Enter h: '))

if r<= 0 or h<= 0:
    print('Numbers can\'t be negative!')
else:
    S = math.pi * r *r
    Volume = math.pi * r * r * h
    print('S = ' + str(S))
    print('V = ' + str(Volume))