from math import isqrt

ceil_sq = lambda n: 1 + isqrt(n - 1)

L, R = map(int, input().split())
res = [True] * (R - L + 1)


def primes(n):
    is_prime = [True] * (n + 1)
    is_prime[0] = False
    is_prime[1] = False
    for i in range(2, int(n**0.5) + 1):
        if not is_prime[i]:
            continue
        for j in range(i * 2, n + 1, i):
            is_prime[j] = False
    return (i for i in range(n + 1) if is_prime[i])


# 10^6以下の素数の2乗で割り切れるかどうかを調べる
for p in primes(10**6 + 1):
    p2 = p**2
    for i in range((L // p2) * p2, R + 1, p2):
        if i < L:
            continue
        res[i - L] = False

# 10^6~10^9の素数の2乗で割り切れるかどうかを調べる
for i in range(1, 10**6 + 1):
    if L < i:
        break
    l_sqrt = ceil_sq(L // i)
    r_sqrt = isqrt(R // i)
    for n in range(l_sqrt, r_sqrt + 1):
        if n <= 1:
            continue
        if L <= i * n**2 <= R:
            res[i * n**2 - L] = False
print(res.count(True))