-- Database schema
| cars : id [ INTEGER ] primary_key , train_id [ INTEGER ] cars.train_id = trains.id , position [ INTEGER ] , shape [ TEXT ] , len [ TEXT ] , sides [ TEXT ] , roof [ TEXT ] , wheels [ INTEGER ] , load_shape [ TEXT ] , load_num [ INTEGER ] | trains : id [ INTEGER ] primary_key , direction [ TEXT ] |
-- -- Please list the directions in which the trains with 4 short cars run.

SELECT T2.direction FROM cars AS T1 INNER JOIN trains AS T2 ON T1.train_id = T2.id WHERE T1.len = 'short' AND T1.position = 4;