L, R = map(int, input().split())
if R == 1:
    print(1)
    exit()

# 素数リスト作成
def PrimeList(N):
    P = [1] * (N + 1)
    P[0] = P[1] = 0
    for i in range(2, N + 1):
        if P[i]:
            for j in range(i + i, N + 1, i):
                P[j] = 0
    PL = []
    for i in range(N + 1):
        if P[i] == 1:
            PL.append(i)
    return PL

PL = PrimeList(10 ** 6)
A = list(range(L, R + 1))

for p in PL:
    p2 = p * p
    for i in range(-(-L // p) * p - L, R // p * p - L + 1, p):
        j = 0
        while A[i] % p == 0:
            if j == 1:
                A[i] = -1
            else:
                A[i] //= p
            j += 1

def check(x, y):
    return x >= y * y

for i in range(R - L + 1):
    a = A[i]
    if a > 1:
        lb = 0
        ub = R
        while ub - lb > 1:
            mid = (ub + lb) // 2
            if check(a, mid):
                lb = mid
            else:
                ub = mid
        if a == lb * lb:
            A[i] = -1
ans = 0
for a in A:
    if a > 0:
        ans += 1
print(ans)