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]]

l, r = map(int, input().split())
k = list(range(l, r + 1))
d = [1] * (r - l + 1)
pr = primes(1000000)
for p in pr:
    x = 1
    while x * p <= r:
        x *= p
        for i in range(l + x - 1 - (l + x - 1) % x, r + 1, x):
            k[i - l] //= p
    t = p * p
    for i in range(l + t - 1 - (l + t - 1) % t, r + 1, t):
        d[i - l] = 0
ans = r - l + 1
for i in range(r - l + 1):
    if d[i] == 0 or (k[i] > 1 and int((k[i]+1)**.5)**2==k[i]):
        ans -= 1
print(ans)