Task: Question Answering
Input (English): Passage: Khuzestan remained much out of the central Persian reach by 1923. He was supported by the British, who sent him some 3,000 arms and additional ammunition by 1919. Sheykh Khazal had been collecting taxes, but in fact paid a very small fraction to the central government. In 1921, realizing the threat posed by Reza Khan Mirpanj , who had just staged a coup d'état with Seyyed Zia'eddin Tabatabaee, Khaz'al proceeded to take steps in order to protect himself. In February 1922, the issue of taxation from tribal areas of Mohammerah was reopened by the Iranian government. Shaykh Khazal and Bakhtiari Khan's met between April 29 and May 2, 1922, in Dar-i Khazinah to establish a cooperation; another meeting between the parties in Ahvaz produced a formal document that Khazal and Bakhtiaris would cooperate in every respect, although both would "continue to serve Iranian government faithfully and loyally". The agreement was an important step which paved the way to the establishment of the Southern League. The nucleus of the alliance, based on Shaykh Khazal and the Bakhtiaris, later tried to attract additional elements, including the Vali of Pusht-i Kuh, Qavam al-Mulk of Khamsah and possibly Sawlat al-Dawlah. The League however had no formal existence, being largely a temporary tribal confederation with common interests. 
Question: Over how many days did Shaykh Khazal and Bakhtiari Khan's meet in Dar-i Khazinah to eastablish a cooperation? 
Answer type: Number 
Output (English): 4.