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

C = 10 ** 6
dat = [0] * C
d = list(range(L,R+1))
for i in range(2,C):
    if dat[i] == 0:
        for j in range(2 * i,C,i):
            dat[j] = 1
        for j in range((L+i-1)//i,R//i+1):
            d[i * j - L] //= i
        now = i * i
        for j in range((L+now-1)//now,R//now+1):
            d[now*j-L] = 0
def check(x):
    if x <= 10 ** 12:return False
    start = 10 ** 6
    end = 10 ** 9 + 1
    while end - start > 1:
        mid = end + start >> 1
        if mid * mid <= x:
            start = mid
        else:
            end = mid
    return start * start == x
ans = 0
for i in d:
    if i == 0:continue
    if i == 1:
        ans += 1
        continue
    if check(i) == False:
        ans += 1
print(ans)