#include <bits/stdc++.h>
using namespace std;
#define modulo 1000000007
#define mod(mod_x) ((((long long)mod_x+modulo))%modulo)
#define Inf 1000000000

struct unionfind{
	vector<int> data;
	vector<int> size;
	unionfind(int n){
		for(int i=0;i<n;i++){
			data.push_back(i);
			size.push_back(1);
		}
	}
	
	int find(int x){
		if(data[x]==x)return x;
		return data[x]=find(data[x]);
	}
	
	bool unite(int x,int y){
		x=find(x);y=find(y);
		if(x==y)return false;
		if(size[x]>size[y])swap(x,y);
		data[x]=y;
		size[y]+=size[x];
		return true;
	}
	
	bool check(int x,int y){
		return (find(x)==find(y));
	}
	
	int get_size(int x){
		int X = find(x);
		return size[X];
	}
};

int main(){
	
	int L,R;
	cin>>L>>R;
	
	unionfind uf(200001);
	
	for(int i=L;i<=R;i++){
		for(int j=i;j<=R;j+=i)uf.unite(i,j);
	}
	set<int> S;
	for(int i=L;i<=R;i++)S.insert(uf.find(i));
	
	cout<<S.size()-1<<endl;
	
	return 0;
}