import numpy as np
a, b = map(int, input().split())
dis = (b - a)/100000
# count = 0
ans = 0
if dis == 0:
    print(0)
else:
    for i in np.arange(a, b, dis):
        # print(((i**2) - ((a + b)*i) + (a*b) ))
        ans += abs((i**2) - ((a + b)*i) + (a*b) )
        # count += 1
        # if count > 95000:
        #     print(i)
    print(ans*dis)