import math
a,b = map(int,input().split(" "))
zero_dev = int(a*b)
zero_sa = int(b-a)
first_wa = int(a-b)
first_multi_u = int(math.pow(b,2))
first_multi_l = int(math.pow(a,2))
second_multi_u = int(math.pow(b,3))
second_multi_l = int(math.pow(a,3))

zero_seki = zero_dev*zero_sa
first_seki = (first_multi_u-first_multi_l)/2
second_seki = (second_multi_u-second_multi_l)/3

print(second_seki-first_seki+zero_seki)