import math

def sieve(n):
    sieve = [True] * (n + 1)
    sieve[0] = sieve[1] = False
    for i in range(2, int(math.isqrt(n)) + 1):
        if sieve[i]:
            sieve[i*i : n+1 : i] = [False] * len(sieve[i*i : n+1 : i])
    primes = [i for i, is_prime in enumerate(sieve) if is_prime]
    return primes

def is_prime(n):
    if n < 2:
        return False
    for p in [2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37]:
        if n % p == 0:
            return n == p
    d = n - 1
    s = 0
    while d % 2 == 0:
        d //= 2
        s += 1
    for a in [2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37]:
        if a >= n:
            continue
        x = pow(a, d, n)
        if x == 1 or x == n - 1:
            continue
        for _ in range(s - 1):
            x = pow(x, 2, n)
            if x == n - 1:
                break
        else:
            return False
    return True

L, R = map(int, input().split())
primes = sieve(10**6)

is_square_free = [True] * (R - L + 1)

for p in primes:
    p_squared = p * p
    if p_squared > R:
        continue
    start = ((L + p_squared - 1) // p_squared) * p_squared
    if start > R:
        continue
    for multiple in range(start, R + 1, p_squared):
        idx = multiple - L
        is_square_free[idx] = False

count = 0
for x in range(L, R + 1):
    idx = x - L
    if not is_square_free[idx]:
        continue
    s = math.isqrt(x)
    if s * s == x:
        if is_prime(s):
            is_square_free[idx] = False
    if is_square_free[idx]:
        count += 1

print(count)