N = 100
prime = []
for i in range(2, N):
    for j in range(2, i):
        if i % j == 0:
            break
    else:
        prime.append(i)
a, b = map(int, input().split())
res = 0
for x in prime:
    if a <= x <= b:
        res += x**3 - x**2 + x + 1
print(res)