a,b=map(int,input().split())
if b-a<10**(-5):
    print(0)
    exit()
s=a+0
w=b-a
ans=0
while a<=s<=b:
    s+=w/(10**5)
    y=(s-a)*(s-b)*(w/(10**5))
    ans+=abs(y)

print(ans)