Soumya wants to buy a tree

Soumya wants to purchase a tree. You have an unrooted tree having $N$ nodes. If you root the tree at node $X$, then Cost of tree = $\sum_{i=1}^n$ {$(-1)$$(dis[i])$ $*A[i] *dis[i]$}, where $dis[i]$ denotes distance of node $i$ from $X$ i.e. the number of edges in the shortest path connecting them. As you are Soumya's friend, you would like to sell her the tree for the least possible cost :) Find ou