a, b = map(int, input().split())
ans = 0
def p(t):
    if t == 1:
        return 0
    for i in range(2, t):
        if t % i == 0:
            return 0
    return 1

def f(t):
    return t*t*t-t*t+t+1

for i in range(a, b+1):
    if p(i):
        ans += f(i)
print(ans)