write a go solution for Description:
You are given a weighted tree (undirected connected graph with no cycles, loops or multiple edges) with n vertices. The edge u_j,v_j has weight w_j. Also each vertex i has its own value a_i assigned to it.

Let's call a path starting in vertex u and ending in vertex v, where each edge can appear no more than twice (regardless of direction), a 2-path. Vertices can appear in the 2-path multiple times (even start and end vertices).

For some 2-path p profit Pr(p)=sumlimits_vindistinctverticesinpa_v-sumlimits_eindistinctedgesinpk_e*w_e, where k_e is the number of times edge e appears in p. That is, vertices are counted once, but edges are counted the number of times they appear in p.

You are about to answer m queries. Each query is a pair of vertices (qu,qv). For each query find 2-path p from qu to qv with maximal profit Pr(p).

Input Format:
The first line contains two integers n and q (2<=n<=3*10^5, 1<=q<=4*10^5) — the number of vertices in the tree and the number of queries.

The second line contains n space-separated integers a_1,a_2,...,a_n (1<=a_i<=10^9) — the values of the vertices.

Next n-1 lines contain descriptions of edges: each line contains three space separated integers u_i, v_i and w_i (1<=u_i,v_i<=n, u_ineqv_i, 1<=w_i<=10^9) — there is edge u_i,v_i with weight w_i in the tree.

Next q lines contain queries (one per line). Each query contains two integers qu_i and qv_i (1<=qu_i,qv_i<=n) — endpoints of the 2-path you need to find.

Output Format:
For each query print one integer per line — maximal profit Pr(p) of the some 2-path p with the corresponding endpoints.

Note:
Explanation of queries:

1. (1,1) — one of the optimal 2-paths is the following: 1arrow2arrow4arrow5arrow4arrow2arrow3arrow2arrow1. Pr(p)=(a_1+a_2+a_3+a_4+a_5)-(2*w(1,2)+2*w(2,3)+2*w(2,4)+2*w(4,5))=21-2*12=9.
2. (4,4): 4arrow2arrow1arrow2arrow3arrow2arrow4. Pr(p)=(a_1+a_2+a_3+a_4)-2*(w(1,2)+w(2,3)+w(2,4))=19-2*10=9.
3. (5,6): 5arrow4arrow2arrow3arrow2arrow1arrow2arrow4arrow6.
4. (6,4): 6arrow4arrow2arrow1arrow2arrow3arrow2arrow4.
5. (3,4): 3arrow2arrow1arrow2arrow4.
6. (3,7): 3arrow2arrow1arrow2arrow4arrow5arrow4arrow2arrow3arrow7.. Output only the code with no comments, explanation, or additional text.