Kiran can do a piece of work in 9 days and Kumar can do the same work in 18 days They started the wo...........

Kiran can do a piece of work in 9 days and Kumar can do the same work in 18 days. They started the work. After 3 days Sanjay joined them, who can complete alone the same whole work in 3 days. What is the total number of days in which they had completed the work?