# How can I obtain representatives of a quotient ring?

I want to compute quotient of integer ring of $\mathbb{Q}(\omega) (\omega^3=1)$ by a prime ideal $(-4-3\omega)$. Especially I want to compute representatives.

```
N=3
x=polygen(ZZ,'x')
K.<a>=CyclotomicField(N)
O = K.ring_of_integers()
p=-4-3*a
R.<b,c>=QuotientRing(O, K.ideal(p))
```

What should I do next?

More, I want to compute its cardinality (=13), But

```
R.cardinality()
```

made error.