0 Kg box of oranges slides from rest down a frictionless incline from a height of 5.

A 9.0 Kg box of oranges slides from rest down a frictionless incline from a height of 5.0 m. A constant frictional force, introduced at point A, brings the block to rest at point B, 19 m to the right of point A. What is the speed of the box just before it reaches point A?