#54011: C++
#include <iostream>
using namespace std;
int main(){
int n,m;
while(cin>>n>>m){
int ans=0;
for(int i=n;i<=m;i++){
int a=0,k=i;
for(int j=3;j<=m;j+=2){
if(k%2==0)break;
while(k%j==0){
k/=j;
a++;
}
}
if(a==1)ans++;
}
cout<<ans<<endl;
}
return 0;
}