def sqrt(n):
    if n == 0: return 0
    x = 1 << (n.bit_length() + 1) // 2
    y = (x + n // x) // 2
    while y < x:
        x = y
        y = (x + n // x) // 2
    return x

N = 10 ** 6
prime_list = [] # 素数リスト
lpf = [0] * (N + 1) # 最小素因数
for i in range(2, N + 1):
    if not lpf[i]:
        lpf[i] = i
        prime_list.append(i)
    a = lpf[i]
    for p in prime_list:
        if p > a or p * i > N: break
        lpf[p*i] = p
# print("lpf =", lpf)
if 0:
    print("prime_list =", prime_list[-20:])
L, R = map(int, input().split())
# L, R = 998877, 998977
n = R - L + 1
A = [i for i in range(L, R + 1)]
if 0:
    print("A =", A)
for p in prime_list:
    l = ((L - 1) // p + 1) * p - L
    for i in range(l, n, p):
        if A[i] < 0: continue
        A[i] //= p
        if A[i] % p == 0:
            A[i] = -1
if 0:
    print("A =", A)
ans = 0
for i in range(n):
    if A[i] < 0 or (A[i] > 1 and sqrt(A[i]) ** 2 == A[i]):
        pass
    else:
        ans += 1
if 0:
    print("A =", A)
print(ans)