def func(a, b, x):
    return (x - a) * (x - b)


N = 10000

a, b = [int(w) for w in input().split()]

d = b-a
ans = 0
for i in range(N):
    ans += abs(func(a, b, a + d * i / N))
    # print(a+d*i/N,"  ",func(a, b, a + d * i / N))

ans = ans * d / N
print(ans)