struct UnionFind {
    n: usize,
    parents: Vec<usize>,
    size: Vec<usize>,
    vals: Vec<isize>,
}

impl UnionFind {
    fn new(n: usize) -> Self {
        UnionFind {
            n: n,
            parents: (0..n).collect(),
            size: vec![1usize; n],
            vals: vec![0isize; n],
        }
    }

    fn equiv(&mut self, a: usize, b: usize) -> bool {
        self.find(a) == self.find(b)
    }
    
    fn unite(&mut self, a: usize, b: usize) {
        if self.equiv(a, b) { return; }
        let (a, b) = (a.min(b), a.max(b));
        let x = self.find(a);
        let y = self.find(b);
        if self.size[x] <= self.size[y] {
            self.size[y] += self.size[x];
            self.size[x] = 0;
            self.vals[x] -= self.vals[y];
            self.parents[x] = self.parents[y];
        } else {
            self.size[x] += self.size[y];
            self.size[y] = 0;
            self.vals[y] -= self.vals[x];
            self.parents[y] = self.parents[x];
        }
    }

    fn find(&mut self, a: usize) -> usize {
        if self.parents[a] == a { return a; }
        let p = self.find(self.parents[a]);
        p
    }

    fn addval(&mut self, idx: usize, val: isize) {
        let idx = self.find(idx);
        self.vals[idx] += val;
    }

    fn getval(&self, idx: usize) -> isize {
        let mut ret = self.vals[idx];
        let mut idx = idx;
        while self.parents[idx] != idx {
            idx = self.parents[idx];
            ret += self.vals[idx];
        }
        ret
    }
}

fn main() {
    let mut lr = String::new();
    std::io::stdin().read_line(&mut lr).ok();
    let lr: Vec<usize> = lr.trim().split_whitespace().map(|s| s.parse().unwrap()).collect();
    let l = lr[0];
    let r = lr[1];

    let mut uf = UnionFind::new(r+1);
    for i in l..r {
        for j in 1.. {
            let val = i*j;
            if val > r { break; }
            uf.unite(i, val);
        }
    }
    let mut result = 0usize;
    for i in l..r {
        if !uf.equiv(i, i+1) {
            result += 1;
            uf.unite(i, i+1);
        }
    }
    println!("{}", result);
}