Finding the distance for one stone to pass the other

[lauren16]

Homework Statement

A stone is dropped from the top of a tall cliff(with zero initial speed), and 1.00s later a second stone is thrown vertically downward w/ a speed of 16 m/s. How far below the top cliff will the second stone overtake the first

Homework Equations

distance = volt + 1/2a(tsquared)

The Attempt at a Solution

I attempted this so many different ways but I'm just not getting the answer. I know the vo of the first stone is zero and the acceleration is -9.8 m/s squared. I think that the second stones initial velocity is 16 m/s.

 

[lauren16]

answer should be 15.7 m by the way