fn main() {
    let v = read_vec::<i128>();
    let (l, r) = (v[0], v[1]);
    let primes = get_primes(1000001);

    let mut flags = vec![true; (r - l) as usize + 1];
    let mut numbers = (l..=r).collect::<Vec<_>>();

    for p in primes {
        let mut cur = (l / p) * p;
        if cur < l {
            cur += p;
        }
        while cur <= r {
            let idx = (cur - l) as usize;
            let mut count = 0;
            while numbers[idx] % p == 0 {
                numbers[idx] /= p;
                count += 1;
            }
            if count >= 2 {
                flags[idx] = false;
            }
            cur += p;
        }
    }

    let mut ans = 0;
    for num in l..=r {
        if num == 1 {
            ans += 1;
            continue;
        }
        if flags[(num - l) as usize] {
            let (ok, ng) = binary_search(0, l + 1, |m| m * m <= num);
            if ok * ok != num {
                ans += 1;
            }
        }
    }
    println!("{}", ans);
}

type Input = i128;
fn binary_search<F>(lb: Input, ub: Input, criterion: F) -> (Input, Input)
where
    F: Fn(Input) -> bool,
{
    assert_eq!(criterion(lb), true);
    assert_eq!(criterion(ub), false);
    let mut ok = lb;
    let mut ng = ub;
    while ng - ok > 1 {
        let mid = (ng + ok) / 2;
        if criterion(mid) {
            ok = mid;
        } else {
            ng = mid;
        }
    }
    (ok, ng)
}

fn read<T: std::str::FromStr>() -> T {
    let mut s = String::new();
    std::io::stdin().read_line(&mut s).ok();
    s.trim().parse().ok().unwrap()
}

fn read_vec<T: std::str::FromStr>() -> Vec<T> {
    read::<String>()
        .split_whitespace()
        .map(|e| e.parse().ok().unwrap())
        .collect()
}

fn get_primes(n: i128) -> Vec<i128> {
    let mut is_prime = vec![true; n as usize + 1];
    let mut primes = Vec::new();
    is_prime[0] = false;
    is_prime[1] = false;

    for i in 2..n + 1 {
        if is_prime[i as usize] {
            primes.push(i);
            let mut j = 2 * i;
            while j <= n {
                is_prime[j as usize] = false;
                j += i;
            }
        }
    }
    primes
}