Problem: 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) = ∑_{v ∈ distinct vertices in  p}{a_v} - ∑_{e ∈ distinct edges in  p}{k_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

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_i ≠ v_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

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

Example

Input

7 6
6 5 5 3 2 1 2
1 2 2
2 3 2
2 4 1
4 5 1
6 4 2
7 3 25
1 1
4 4
5 6
6 4
3 4
3 7


Output

9
9
9
8
12
-14

Note

Explanation of queries: 

  1. (1, 1) — one of the optimal 2-paths is the following: 1 → 2 → 4 → 5 → 4 → 2 → 3 → 2 → 1. 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): 4 → 2 → 1 → 2 → 3 → 2 → 4. 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): 5 → 4 → 2 → 3 → 2 → 1 → 2 → 4 → 6. 
  4. (6, 4): 6 → 4 → 2 → 1 → 2 → 3 → 2 → 4. 
  5. (3, 4): 3 → 2 → 1 → 2 → 4. 
  6. (3, 7): 3 → 2 → 1 → 2 → 4 → 5 → 4 → 2 → 3 → 7. 

Solution (in CPP):

Solution:
#include <bits/stdc++.h>
using namespace std;
void scanint(int &x) {
  int c = getchar_unlocked();
  x = 0;
  while (((c < 48 || c > 57))) c = getchar_unlocked();
  for (; c > 47 && c < 58; c = getchar_unlocked()) {
    x = (x << 1) + (x << 3) + c - 48;
  }
}
const int N = 4e5 + 400, LOGN = 19;
int n, q, a[N], dpLCA[LOGN][N], lca[N], kraw[N], dist[N];
vector<pair<int, int> > G[N];
long long dp[N], dp2[N], tree[N], odl[N], wynik[N], pom[N];
vector<int> zapytania[N];
void insert(int v, long long x) {
  while (v <= n) {
    tree[v] += x;
    v += (v & (-v));
  }
}
long long query(int v) {
  long long wynik = 0;
  while (v > 0) {
    wynik += tree[v];
    v -= (v & (-v));
  }
  return wynik;
}
long long pytaj(int a, int b) {
  if (a > b) return 0;
  return query(b) - query(a - 1);
}
void preDFS(int u) {
  dp[u] = a[u];
  for (auto v : G[u]) {
    if (v.first != dpLCA[0][u]) {
      dpLCA[0][v.first] = u;
      dist[v.first] = dist[u] + 1;
      odl[v.first] = odl[u] + v.second;
      kraw[v.first] = v.second;
      preDFS(v.first);
      pom[v.first] = max(0LL, dp[v.first] - 2 * v.second);
      dp[u] += pom[v.first];
    }
  }
}
int LCA(int a, int b) {
  if (dist[a] < dist[b]) swap(a, b);
  int d = dist[a] - dist[b];
  for (int i = 0; i < LOGN; i++)
    if (d & (1 << i)) a = dpLCA[i][a];
  if (a == b) return a;
  for (int i = LOGN - 1; i >= 0; i--) {
    if (dpLCA[i][a] != dpLCA[i][b]) {
      a = dpLCA[i][a];
      b = dpLCA[i][b];
    }
  }
  return dpLCA[0][a];
}
void preDP(int u) {
  int ojciec = dpLCA[0][u];
  dp2[u] = dp[u] + (u != 1 ? max(0LL, dp[ojciec] - 2 * kraw[u]) : 0);
  long long blep = dp[u] - (u != 1 ? pom[u] : 0);
  insert(dist[u], blep);
  for (auto ID : zapytania[u]) wynik[ID] += pytaj(dist[lca[ID]], dist[u]);
  for (auto v : G[u]) {
    if (v.first != dpLCA[0][u]) {
      long long pomek = dp[u];
      dp[u] = dp2[u] - pom[v.first];
      preDP(v.first);
      dp[u] = pomek;
    }
  }
  insert(dist[u], -blep);
}
int32_t main() {
  scanint(n);
  scanint(q);
  for (int i = 1; i <= n; i++) scanint(a[i]);
  for (int i = 1; i < n; i++) {
    int a, b, c;
    scanint(a);
    scanint(b);
    scanint(c);
    G[a].push_back({b, c});
    G[b].push_back({a, c});
  }
  dpLCA[0][1] = 1;
  dist[1] = 1;
  preDFS(1);
  for (int i = 1; i < LOGN; i++)
    for (int j = 1; j <= n; j++) dpLCA[i][j] = dpLCA[i - 1][dpLCA[i - 1][j]];
  for (int i = 1; i <= q; i++) {
    int a, b;
    scanint(a);
    scanint(b);
    lca[i] = LCA(a, b);
    wynik[i] = -(odl[a] + odl[b] - 2 * odl[lca[i]]);
    zapytania[a].push_back(i);
    zapytania[b].push_back(i);
  }
  preDP(1);
  for (int i = 1; i <= q; i++) {
    int u = lca[i];
    int ojciec = dpLCA[0][u];
    wynik[i] = wynik[i] - dp[u];
    long long pomek = dp[ojciec];
    dp[ojciec] = dp2[ojciec] - pom[u];
    printf("%lld\n",
           wynik[i] +
               (u != 1 ? max(0LL, dp[ojciec] - 2 * kraw[u]) + 2 * pom[u] : 0));
    dp[ojciec] = pomek;
  }
  getchar();
  getchar();
  return 0;
}