How to acess the sea parton content in LHAPDF?

I recently install and implemented the LHAPDF in my program of c++ for the cross-sections calculations. But, I am interested in to see the individuals contribuitions of sea quarks and valence quarks. I know that each PDF pdf->xfxQ2(i, x, Q2) has the valence + sea content.

How can I acess these individuals contents?

Because, the valence, for example, to the proton, are in i = 1 (up) and i=2 (down). So, I need the valence part of the pdf->xfxQ2(i=1, 2, x, Q2) and I need the sea part of

pdf->xfxQ2(i=-5, -4, -3, -2, -1, 1, 2, 3, 4, 5, x, Q2)

And, in the sea part we have also the gluons pdf->xfxQ2(21, x, Q2).

Can anyone help me?

I am expect an explanation about the structure of LHAPDF.