The critical edition of the Mahabharata developed by the Bhandarkar Oriental Research Institute (BORI) is collated from 1,259 ancient manuscripts and consists of 18 Parvas and more than 89000 verses (excluding the Harivamsa). The Institute began its project for creating a critical edition on 1 April 1919 and the project was completed on 22 September 1966. The work on Harivamsa took another five years, and was completed in November, 1971.
Here’s the opening mantra of the Mahabharata:
नारायणं नमस्कृत्य नरं चैव नरोत्तमम्
देवीं सरस्वतीं चैव ततो जयम् उदीरयेत्
Om! Having bowed down to Narayana and Nara, the most exalted male being,
and also to the goddess Saraswati, must the word Jaya (victory) be uttered.