import sys
read=sys.stdin.buffer.read
readline=sys.stdin.buffer.readline
readlines=sys.stdin.buffer.readlines
import math
def prime_sieve(n):
    isprime=[True]*(n+1)
    isprime[0]=False
    isprime[1]=False
    for i in range(2, n+1):
        if isprime[i]:
            for j in range(2*i, n+1, i):
                isprime[j]=False
    return isprime
isprime=prime_sieve(1000000)
l, r=map(int, readline().split())
v=list(range(l, r+1))
sqf=[True]*(r-l+1)
for p in range(2, 1000000):
    if not isprime[p]:
        continue
    for i in range((l+p-1)//p*p, r+1, p):
        if not sqf[i-l]:
            continue
        v[i-l]//=p
        if v[i-l]%p==0:
            sqf[i-l]=False
ans=0
for i in range(r-l+1):
    if not sqf[i]:
        continue
    if v[i]==1:
        ans+=1
        continue
    sq=int(math.sqrt(v[i]))
    ans+=1
    for j in range(sq, sq+2):
        if j*j==v[i]:
            ans-=1
            break
print(ans)