Problem Link : http://lightoj.com/volume_showproblem.php?problem=1197

/*
     If opportunity doesn't knock, build a door.

            +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
            |S|.|S|.|R|.|A|.|S|.|A|.|M|.|K|
            +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

    Success is how high you bounce when you hit bottom.
*/


#include <bits/stdc++.h>

#define pii              pair <int,int>
#define pll              pair <long long,long long>
#define sc               scanf
#define pf               printf
#define Pi               2*acos(0.0)
#define ms(a,b)          memset(a, b, sizeof(a))
#define pb(a)            push_back(a)
#define MP               make_pair
#define db               double
#define ll               long long
#define EPS              10E-10
#define ff               first
#define ss               second
#define sqr(x)           (x)*(x)
#define D(x)             cout<<#x " = "<<(x)<<endl
#define VI               vector <int>
#define DBG              pf("Hi\n")
#define MOD              1000000007
#define CIN              ios_base::sync_with_stdio(0); cin.tie(0)
#define SZ(a)            (int)a.size()
#define sf(a)            scanf("%d",&a)
#define sfl(a)           scanf("%lld",&a)
#define sff(a,b)         scanf("%d %d",&a,&b)
#define sffl(a,b)        scanf("%lld %lld",&a,&b)
#define sfff(a,b,c)      scanf("%d %d %d",&a,&b,&c)
#define sfffl(a,b,c)     scanf("%lld %lld %lld",&a,&b,&c)
#define stlloop(v)       for(__typeof(v.begin()) it=v.begin();it!=v.end();it++)
#define loop(i,n)        for(int i=0;i<n;i++)
#define REP(i,a,b)       for(int i=a;i<b;i++)
#define RREP(i,a,b)      for(int i=a;i>=b;i--)
#define TEST_CASE(t)     for(int z=1;z<=t;z++)
#define PRINT_CASE       printf("Case %d: ",z)
#define CASE_PRINT       cout<<"Case "<<z<<": "
#define all(a)           a.begin(),a.end()
#define intlim           2147483648
#define infinity         (1<<28)
#define ull              unsigned long long
#define gcd(a, b)        __gcd(a, b)
#define lcm(a, b)        ((a)*((b)/gcd(a,b)))

using namespace std;


/*----------------------Graph Moves----------------*/
//const int fx[]={+1,-1,+0,+0};
//const int fy[]={+0,+0,+1,-1};
//const int fx[]={+0,+0,+1,-1,-1,+1,-1,+1};   // Kings Move
//const int fy[]={-1,+1,+0,+0,+1,+1,-1,-1};  // Kings Move
//const int fx[]={-2, -2, -1, -1,  1,  1,  2,  2};  // Knights Move
//const int fy[]={-1,  1, -2,  2, -2,  2, -1,  1}; // Knights Move
/*------------------------------------------------*/

/*-----------------------Bitmask------------------*/
//int Set(int N,int pos){return N=N | (1<<pos);}
//int reset(int N,int pos){return N= N & ~(1<<pos);}
//bool check(int N,int pos){return (bool)(N & (1<<pos));}
/*------------------------------------------------*/

#define maxx 100005
bitset<maxx>vis;

vector<int>prime;

void sieve()
{

    int x=maxx/2, y=sqrt(maxx)/2;
    for(int i=1;i<=y;i++)
    {
        if(vis[i])
        {
            for(int j=(i*(i+1))*2;j<=x;j+=(2*i)+1)
                vis[j]=1;
        }
    }
    prime.pb(2);
    for(int i=3;i<maxx;i+=2)
        if(vis[i/2]==0)
            prime.pb(i);
}

int segmented_sieve(int a, int b)
{
    vis=0;
    if(b<2) return 0;
    if(a<2) a=2;
    int xx=sqrt((double)b)+1;
    for(ll i=0;i<SZ(prime) && prime[i]<=xx;i++)
    {
        ll j=(a/prime[i]);
        if(a%prime[i]!=0) j++;
        j*=prime[i];
        if(j==prime[i]) j+=prime[i];
        for(;j<=b;j+=prime[i])
            vis[j-a]=1;
    }
    int cnt=0;
    for(ll i=a;i<=b;i++)
        if(vis[i-a]==0) cnt++;
    return cnt;
}

int main()
{

     ///freopen("in.txt","r",stdin);
    ///freopen("out.txt","w",stdout);
    sieve();
    int t;
    sf(t);
    TEST_CASE(t)
    {
        ll a,b;
        sffl(a,b);
        PRINT_CASE;
        printf("%d\n",segmented_sieve(a,b));
    }
    return 0;
}