a, b = list(map(int, input().split(' ')))

def f(x):
    global a
    global b
    return (x - a) * (x - b)

N = 10 ** 4

c = b - a
ans = 0
for i in range(1, N + 1):
    ans -= (c * f(a + (c * i) / N)) / N

print(ans)