Using Pythagoras theorem,
Altitude^2 + Base^2 = Hypotenuse^2
Altitude = Distance Traveled South 
Base = Distance traveled west
Hypotenuse = Displacement vector 
Putting the values,
1600^2 + 6300^2 = 42250000 
Displacement vector = (422550000)^1/2 = 6500
So, no discount.