500
Conjugate out ALL THREE of the irregular verbs in all 5 tenses in the imperfect.
Ver: veia, veias, veia, veiamos, veian (accent over the "i" in all forms)
Ir: iba, ibas, iba, ibamos (accent over the "i"), iban
Ser: era, eras, era, eramos (accent over the "e"), eran