What is the latecomer (Masbuq) legally required to do regarding the concluding Salaams of the Imam?

Etiquettes of Prayer: Finger Gesture, Supplications, and Other Adab

• Stand up as soon as the Imam starts his first Salaam.
• Wait for the Imam to fully conclude both Salaams before standing up to complete the missed units.
• Perform Salaam along with the Imam and then repeat their entire prayer.
• Go directly into prostration.