Mathematics · Time and Work

Yash can do a piece of work in 49 days, Naman can do the same work in 35 days, and Saurav can do it in 7 days. Find the total number of days required to complete the work if they work on alternate days such that Yash works on the first day, Naman works on the second day, Saurav works on the third day, and then again Yash works on the fourth day and so on.