#include<bits/stdc++.h>
using namespace std;
#define int long long
#define rep(i,n) for(int i=0;i<n;i++)
#define REP(i,n) for(int i=1;i<n;i++)
#define all(v) v.begin(),v.end()
#define P pair<int,int>
#define len(s) (int)s.size()
#define pb push_back

template<class T> inline bool chmin(T &a, T b){
	if(a>b){a=b;return true;}
	return false;
}
template<class T> inline bool chmax(T &a, T b){
	if(a<b){a=b;return true;}
	return false;
}
constexpr int mod = 1e9+7;
constexpr int inf = 3e18;

struct UnionFind{
	vector<int>par,size;
	int find(int x){
		return (par[x]==x?x:par[x]=find(par[x]));
	}
	void merge(int x,int y){
		x=find(x);y=find(y);
		if(x==y)return;
		if(size[x]<size[y]){
			par[x]=y;
			size[y]+=size[x];
		}else {
			par[y]=x;
			size[y]+=size[x];
		}
	}
	bool same(int x,int y){
		return find(x)==find(y);
	}
	UnionFind(int x){
		rep(i,x){
			par.pb(i);size.pb(1);
		}
	}
};
int L,R;
signed main(){
	cin>>L>>R;
	int ans=0;
	UnionFind uf(R-L+1);
	for(int i=L;i<=R;i++){
		for(int j=2;i*j<=R;j++){
			uf.merge(i-L,i*j-L);
		}
	}
	rep(i,R-L+1){
		ans+=uf.find(i)==i;
	}
	cout<<ans-1<<endl;
}