#include<bits/stdc++.h>
#define MAX 5000009
 
using namespace std;
 
bool check[MAX];
 
int sum_of_factors[MAX],DePrimes[MAX];
 
void solve()
{
    int i,j;
 
    for(i=4;i<MAX;i+=2)
    {
        sum_of_factors[i]+=2;
 
        check[i] = true;
    }
 
    for(i=3;i<=2238;i+=2)
    {
        if(!check[i])
        {
            for(j=i*i;j<=MAX;j+=i+i)
            {
                check[j] = true;
            }
        }
    }
 
    for(i=3;i<MAX;i+=2)
    {
        if(!check[i])
        {
            for(j=i;j<=MAX;j+=i)
            {
                sum_of_factors[j]+=i;
            }
        }
    }
 
    DePrimes[0]=DePrimes[1]=0;
 
    sum_of_factors[2] = 2;
 
    for(i=2;i<MAX;i++)
    {
        if(!check[sum_of_factors[i]])
        {
            DePrimes[i] = 1;
        }
 
        DePrimes[i]+=DePrimes[i-1];
    }
}
 
 
int main()
{
    solve();
 
    int a,b;
 
    while(scanf("%d",&a)&&a)
    {
        scanf("%d",&b);
 
        printf("%d\n",DePrimes[b]-DePrimes[a-1]);
    }
 
    return 0;
}