#include <bits/stdc++.h>
using namespace std;
template<typename T1,typename T2> inline void chmin(T1 &a,T2 b){if(a>b) a=b;}
template<typename T1,typename T2> inline void chmax(T1 &a,T2 b){if(a<b) a=b;}
using Int = long long;
const char newl = '\n';


struct UnionFind{
  int num;
  vector<int> rs,ps;
  UnionFind(){}
  UnionFind(int n):num(n),rs(n,1),ps(n,0){iota(ps.begin(),ps.end(),0);}
  int find(int x){
    return (x==ps[x]?x:ps[x]=find(ps[x]));
  }
  bool same(int x,int y){
    return find(x)==find(y);
  }
  void unite(int x,int y){
    x=find(x);y=find(y);
    if(x==y) return;
    if(rs[x]<rs[y]) swap(x,y);
    rs[x]+=rs[y];
    ps[y]=x;
    num--;
  }
  int size(int x){
    return rs[find(x)];
  }
  int count() const{
    return num;
  }
};

//INSERT ABOVE HERE
signed main(){
  cin.tie(0);
  ios::sync_with_stdio(0);

  int l,r;
  cin>>l>>r;

  UnionFind uf(r+1);

  for(int i=l;i<=r;i++)
    for(int j=i;j<=r;j+=i)
      uf.unite(i,j);

  cout<<uf.count()-l-1<<endl;
  return 0;
}