A ball is thrown vertically into the air and takes 5s to return to the thrower, from time of projection. What is the time it takes to reach maximum height ?

Ignoring air resistance, it takes the same time to go up (from initial velocity v to zero) as it takes to go down from the same height (from initial velocity zero to v).

So how long does it take to reach the maximum height if the total time is 5 seconds?