#include<iostream>
#include<stdio.h>
#include<math.h>
using namespace std;
long long Massive[168]={2,3,5,7,11,13,17,19,23,29,31,37,41,43,47,53,59,61,67,71,73,79,83,89,97,101,103,107,109,113,127,131,137,139,149,151,157,163,167,173,179,181,191,193,197,199,211,223,227,229,233,239,241,251,257,263,269,271,277,281,283,293,307,311,313,317,331,337,347,349,353,359,367,373,379,383,389,397,401,409,419,421,431,433,439,443,449,457,461,463,467,479,487,491,499,503,509,521,523,541,547,557,563,569,571,577,587,593,599,601,607,613,617,619,631,641,643,647,653,659,661,673,677,683,691,701,709,719,727,733,739,743,751,757,761,769,773,787,797,809,811,821,823,827,829,839,853,857,859,863,877,881,883,887,907,911,919,929,937,941,947,953,967,971,977,983,991,997};
long long IsPrime(int t)
{
    long long h,flac=0,p;
    h=sqrt(t);
    if(t==1) return 0;
    for(p=0;p<168;p++)
    {
        if(Massive[p]>h) break;
        if(t%Massive[p]==0){flac=1;break;}
    }
    if(flac==1) return 0;
    if(flac==0) return 1;
}

int main()
{
    long long k,a,b,i,j,br=0;
    cin>>k;
    for(i=1;i<=k;i++)
    {
        scanf("%lld %lld", &a,&b);
        for(j=a;j<=b;j++)
        {
            if(IsPrime(j)==1) br++;
        }
        printf("%lld\n", br);
        br=0;
    }
    return 0;
}