# Irregular Distances

Let us say there are train stations named A, B, C, D, and E. Here are the conditions: The distance between A and B is 10 km, the distance between B and C is 9 km, the distance between C and D is 8 km, and the distance between D and E is 13 km. If the distance between A and E isn't 40 km, then how much is the distance?