import math

def sieve_segment(n):
    if n < 2:
        return []
    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])
    return [i for i, is_p in enumerate(sieve) if is_p]

def segmented_sieve(n):
    if n < 2:
        return []
    sqrt_n = int(math.isqrt(n))
    small_primes = sieve_segment(sqrt_n)
    primes = []
    segment_size = sqrt_n
    low = 2
    while low <= n:
        high = min(low + segment_size - 1, n)
        sieve = [True] * (high - low + 1)
        for p in small_primes:
            start = max(p * p, ((low + p - 1) // p) * p)
            start -= low
            if start < 0:
                start += p
            for j in range(start, len(sieve), p):
                sieve[j] = False
        for i in range(len(sieve)):
            if sieve[i]:
                primes.append(low + i)
        low = high + 1
    return primes

L, R = map(int, input().split())

size = R - L + 1
is_square_free = [True] * size

max_p = int(math.isqrt(R))
primes = segmented_sieve(max_p)

for p in primes:
    s = p * p
    if s > R:
        continue
    first = ((L + s - 1) // s) * s
    if first > R:
        continue
    start_idx = first - L
    step = s
    for idx in range(start_idx, size, step):
        is_square_free[idx] = False

print(sum(is_square_free))