Proton-Antiproton Annihilation

[Skatch]

Homework Statement

A proton and antiproton at rest in an S-state annihilate to produce \pi⁰\pi⁰ pairs. Show
that this reaction cannot be a strong interaction.

Homework Equations

I interpret this problem as:

p + p_bar -> \pi⁰ + \pi⁰

The Attempt at a Solution

If this were a strong interaction, Parity should be conserved, yes? I think that in the annihilation
described above, parity is not being conserved.But really, my first question is, am I interpreting it correctly? Is the annihiliation producing \pi⁰ + \pi⁰?
Or is it producing \pi⁰ + \pi⁰ + \pi⁰ + \pi⁰? Not sure what they mean by "\pi⁰\pi⁰ pairs".Then my next question is, what is the Parity of p_bar?

 

[Skatch]

Okay, so I think I've come to the conclusion that the Parity of the antiproton is -1.
I read that, in general, P(fermion * antifermion) = -1, and since proton's parity is +1, I'm
going to conclude that parity of the antiproton is -1.

Okay, so total parity on the left hand side of the equation is 0.

But I still don't know if I'm interpreting the problem correctly. Is the annihilation producing:

\pi⁰ + \pi⁰ ?

\pi⁰ + \pi⁰ + \pi⁰ + \pi⁰ ?

\pi⁰\pi⁰ ?

\pi⁰\pi⁰ + \pi⁰\pi⁰ ?

Pardon the ignorance here. I'm taking this Nuclear Physics class despite not meeting some
of the pre-reqs. I'm a math major that was just interested in the material, so I'm a bit
behind.

Thanks for any help.