Two gas appliances are vented with a common vent. One is a 3″ vent connector. The other is a 5″ vent connector. The minimum size common vent required to vent these two appliances is ____.

Two gas appliances are vented with a common vent. One is a 3″ vent connector. The other is a 5″ vent connector. The minimum size common vent required to vent these two appliances is ____.