How does one complete the prayer if they joined the Imam after he had already prayed one or more rak'ahs?

A latecomer to congregational prayer (masbuq), whether missing one rak'ah or more, continues praying with the Imam until he says the tasleem. Then, he completes what he missed after the Imam’s tasleem, based on the Prophet's (peace be upon him) saying: "So whatever you catch up with, pray, and whatever you miss, complete." Therefore, he should envision himself as praying alone, having already prayed two or three rak'ahs, and then he completes the remainder.