#include<iostream>
using namespace std;
#include<vector>
struct UF{
	int n;
	vector<int>parent,rank;
	UF(int n_=0):n(n_),parent(n_),rank(n_,1)
	{
		for(int i=0;i<n_;i++)parent[i]=i;
	}
	int find(int a){return parent[a]!=a?parent[a]=find(parent[a]):a;}
	bool same(int a,int b){return find(a)==find(b);}
	bool unite(int a,int b)
	{
		a=find(a),b=find(b);
		if(a==b)return false;
		if(rank[a]<rank[b])
		{
			parent[a]=b;
			rank[b]+=rank[a];
		}
		else
		{
			parent[b]=a;
			rank[a]+=rank[b];
		}
		return true;
	}
	int size(int a){return rank[find(a)];}
};
int L,R;
main()
{
	cin>>L>>R;
	UF uf(R+1);
	int ans=R-L;
	for(int i=L;i<=R;i++)
	{
		for(int j=i+i;j<=R;j+=i)
		{
			ans-=uf.unite(i,j);
		}
	}
	cout<<ans<<endl;
}