# put your python code here

a = int(input())
b = int(input())
mean = 0
count = 0

for i in range(a, b + 1):
    if i % 3 == 0:
        mean += i
        count += 1

print(mean / count)

ab3b09e5ef161f08dd3643aea9a94367322802e1
<mask token>

<mask token>
for i in range(a, b + 1):
    if i % 3 == 0:
        mean += i
        count += 1
print(mean / count)

a = int(input())
b = int(input())
mean = 0
count = 0
for i in range(a, b + 1):
    if i % 3 == 0:
        mean += i
        count += 1
print(mean / count)

# put your python code here

a = int(input())
b = int(input())
mean = 0
count = 0

for i in range(a, b + 1):
    if i % 3 == 0:
        mean += i
        count += 1

print(mean / count)
