Yes counting stops is good advice. But one first must determine the point of origin. Three maps in hand and full knowledge the desired stop is two stops on the green line / line 2 after arriving via the airport express from DME. Despite watching trains go by for over an hour the method to determine which train is the green line and/or which train is line 2 is still a mystery. Three maps in hand were of little value. No clear indication of line or stop interior to train. No clear indication of line or stop exterior to train. As a point of reference, quickly mastered subways system in Beijing, Hong Kong, Seoul, London, Madrid, Vienna & Frankfurt.