There are N (2 ≤ N ≤ 100,000) poles, each with some height_i meters (1 ≤ height_i ≤ 100). You should connect the tops of each pair of adjacent poles and will incur a penalty cost C × the two poles' height difference for each section of wire where the poles are of different heights (1 ≤ C ≤ 100). The poles, of course, are in a certain sequence and can not be moved.

In addition , if you makes some poles taller you can reduce your penalties, though with some other additional cost. You can add an integer X number of meters to a pole at a cost of X².

Line 1: Two space-separated integers: N and C
       Lines 2 ~ N+1: Line i+1 contains a single integer: height_i .

Line 1: The minimum total amount of money that it will cost to connect all of the poles.