//---------- begin union_find ----------
#[allow(dead_code)]
mod union_find {
    pub struct UF {
        p: Vec<i32>,
    }
    impl UF {
        pub fn new(n: usize) -> UF {
            UF {p: vec![-1; n] }
        }
        pub fn init(&mut self) {
            for p in self.p.iter_mut() {
                *p = -1;
            }
        }
        pub fn root(&mut self, mut x: usize) -> usize {
            while self.p[x] >= 0 {
                let p = self.p[x] as usize;
                if self.p[p] < 0 {
                    return p;
                }
                let q = self.p[p] as usize;
                self.p[x] = q as i32;
                x = q;
            }
            x
        }
        pub fn unite(&mut self, mut x: usize, mut y: usize) -> Option<(usize, usize)> {
            x = self.root(x);
            y = self.root(y);
            if x == y {
                return None;
            }
            if self.p[x] > self.p[y] {
                let s = x;
                x = y;
                y = s;
            }
            self.p[x] += self.p[y];
            self.p[y] = x as i32;
            Some((x, y))
        }
    }
}
//---------- end union_find ----------

fn run() {
    let mut s = String::new();
    std::io::stdin().read_line(&mut s).unwrap();
    let mut it = s.trim().split_whitespace();
    let l: usize = it.next().unwrap().parse().unwrap();
    let r: usize = it.next().unwrap().parse().unwrap();
    let mut ans = r - l;
    let mut u = union_find::UF::new(r + 1);
    for i in l..=r {
        let mut j = 2 * i;
        while j <= r {
            if u.unite(i, j).is_some() {
                ans -= 1;
            }
            j += i;
        }
    }
    println!("{}", ans);
}

fn main() {
    run();
}