Sandhya starts from her home and goes 15 km towards East. She now takes a right turn and goes 10 km. She again takes a right turn and goes 15 km to reach Reena’s house. At Reena’s house she takes a left turn and goes 10 km. Finally she takes a left turn and goes 15 km to reach Parul’s house. What is the shortest distance between Sandhya’s house and Parul’s house?