#include <iostream>
using namespace std;

bool pierwsza(unsigned x)
{
    for(int i = 2; i * i <= x; ++i)
        if(x % i == 0)
            return false;
    return true;
}

unsigned ile_pierwszych(unsigned a, unsigned b)
{
    unsigned wynik = 0;
    for(unsigned i = a; i <= b; ++i)
        if(pierwsza(i))
            ++wynik;
    return wynik;
}

int main()
{
    short n;
    cin >> n;
    unsigned tablica[2 * n];
    for(unsigned short i = 0; i < 2 * n; ++i)
        cin >> tablica[i];

    for(unsigned short i = 0; i < 2 * n; ++i)
    {
        cout << ile_pierwszych(tablica[i], tablica[i + 1]) << endl;
        ++i;
    }
}