else:
    while True:
        start = comm.recv(source=0, tag=1)
        if start == -1: break

        i = 0
        slice_value = 0
        while i < slice_size:
            if i%2 == 0:
                slice_value += 1.0 / (2*(start*slice_size+i)+1)
            else:
                slice_value -= 1.0 / (2*(start*slice_size+i)+1)
            i += 1

        comm.send(slice_value, dest=0, tag=1)
        comm.send(rank, dest=0, tag=2)