# a = list(input().split())
# a.reverse()
# print(*a)
a, b = list(map(int, input().split()))
k = 0
t = 0
x = [i for i in range(a, b + 1) if i % 3 == 0]
y = [i for i in range(a, b + 1) if i % 4 == 0]
for i in range(len(x)):
k += x[i]
for i in range(len(y)):
t += y[i]
print(k + (-t))