#include <bits/stdc++.h>
using namespace std;
using ll = long long;
template <class T, class U> using Pa = pair<T, U>;
template <class T> using vec = vector<T>;
template <class T> using vvec = vector<vec<T>>;

class UnionFind{
private:
    vec<int> p,s;
    int cnt;
public:
    UnionFind(){}
    UnionFind(int N):cnt(N),s(N,1),p(N){
        iota(p.begin(),p.end(),0);
    }
    int find(int x){
        if(p[x]==x) return x;
        else return p[x] = find(p[x]);
    }
    void unite(int x,int y){
        x = find(x); y = find(y);
        if(x==y) return;
        if(s[x]>s[y]) swap(x,y);
        p[x] = y;
        s[y] += s[x];
        cnt--;
    }
    bool is_same_set(int x,int y) {return find(x)==find(y);}
    int size(int x) {return s[find(x)];}
    int compnents_number(){return cnt;}
};

int main(){
    cin.tie(0);
    ios::sync_with_stdio(false);
    int L,R;
    cin >> L >> R;
    UnionFind uf(R+1);
    for(int i=L;i<=R;i++){
        for(int j=2;i*j<=R;j++) uf.unite(i,i*j);
    }
    cout << uf.compnents_number()-L-1 << "\n";
}