Gravitational Potential Energy (again)

Joe has mass m = 60 kg. He goes to the construction site and wanders around to check for structural damage. Can you compute the change in Joe's gravitational potential energy as Joe goes from A to C by the following paths? Please include the units.

1. Joe climbs from A to B, then walks across from B to Z.
2. Joe walks across from A to C, then climbs up from C to Z.
3. Joe walks up the ramp from A to Z.

Are all these changes the same? Why or why not?