`A, B, C` are 3 towns forming a triangle. A man has to walk from one town to the next town, then ride in the next, and then again drive towards his starting point. He can walk, ride and drive `a` km in `a, b, c` minutes respectively. If he starts from `B`, he takes `a+c-b` hours, if he starts from `C`, he takes `b+a-c` hours, and if he starts from `A`, he takes `c+b-a` hours. The length of the triangle is (Assume the motion to be anticlockwise).