long computeCase(Pair[] arr)
{
    arr.sort();
    double k = 0.0;
    long count = 1;

    while(true)
    {
        auto switches = iota(arr.length-1)
                        .map!(i => tuple!("a", "b", "c", "d", "id")(arr[i].a, arr[i].b, arr[i+1].a, arr[i+1].b, i))
                        .filter!(e => e.b != e.d)
                        .map!(e => tuple!("f", "id")(cast(double)(e.c - e.a) / (e.b - e.d), e.id))
                        .filter!(e => e.f > k);
        if(switches.empty)
            break;
        auto bestSwitch = switches.minElement;
        swap(arr[bestSwitch.id], arr[bestSwitch.id+1]);
        k = bestSwitch.f;
        count++;
    }

    return count;
}