Is it sufficient for one who prays a supererogatory prayer with the Imam in the Maghrib prayer to pray three rak’ahs, or should he add a fourth rak’ah to make it an even number?

Scholars differ regarding the re-performance of congregational prayer. The Malikis hold that it is not prescribed, while the Hanbalis and Shafi'is deem it recommended to re-perform it. If a worshiper re-performs the Maghrib prayer in congregation after having prayed it [individually], he adds one rak'ah to his prayer, and the prayer he performed alone is considered the obligatory one.