A doctor is located at X and his hospital is located at Y. There is no straight lane from the house to the hospital. Therefore the doctor first goes to A which is 500m due east of X, then goes to B which is 400m due south of A, then to C which is 90m due west of B and finally reaches the hospital at Y which is 80m due north of C. With respect to the hospital the correct direction of the doctor's house is