#include <bits/stdc++.h>
using namespace std;
const int MAXN = 2e5 + 5;
const long long mod = 1e9 + 7;
int n;
long long value[MAXN];
vector<int> graph[MAXN];
long long pathSum, pathCnt;
long long currSum, currCnt;
bool isCentroid[MAXN];
int treeSize[MAXN];
long long answer = 0;
long long cnt[MAXN], sum[MAXN];
void DFSInit(int x, int last) {
  treeSize[x] = 1;
  for (int i = 0; i < graph[x].size(); i++) {
    if (graph[x][i] == last || isCentroid[graph[x][i]] == true) continue;
    DFSInit(graph[x][i], x);
    treeSize[x] += treeSize[graph[x][i]];
  }
}
int findCentroid(int root) {
  int last = root;
  int centroid = root;
  DFSInit(root, -1);
  while (true) {
    bool found = false;
    for (int i = 0; i < graph[centroid].size(); i++) {
      if (isCentroid[graph[centroid][i]] == false &&
          treeSize[graph[centroid][i]] > treeSize[root] / 2 &&
          graph[centroid][i] != last) {
        found = true;
        last = centroid;
        centroid = graph[centroid][i];
        break;
      }
    }
    if (found == false) {
      break;
    }
  }
  return centroid;
}
void DFSLoad(int x, int last, long long sum, int depth, bool mode) {
  if (isCentroid[x] == true) return;
  sum = (sum + ((depth % 2 == 1) ? value[x] : -value[x]) + mod) % mod;
  if (mode == false) {
    answer = (answer + sum) % mod;
    pathCnt++;
    pathSum = (pathSum + sum) % mod;
  }
  currCnt++;
  currSum = (currSum + sum) % mod;
  for (int i = 0; i < graph[x].size(); i++) {
    if (graph[x][i] == last) continue;
    DFSLoad(graph[x][i], x, sum, depth + 1, mode);
  }
}
void DFSCalc(int x, int last, long long sum, int depth, int centroid) {
  if (isCentroid[x] == true) return;
  if (depth != 1) {
    answer =
        (answer + sum +
         ((depth % 2 == 0) ? -value[centroid] : value[centroid]) + 2 * mod) %
        mod;
    if (depth % 2 == 0) {
      answer = (answer + sum * (pathCnt) % mod - pathSum + 2 * mod) % mod;
    } else {
      answer = (answer + sum * (pathCnt) % mod + pathSum) % mod;
    }
  }
  for (int i = 0; i < graph[x].size(); i++) {
    if (graph[x][i] == last) continue;
    DFSCalc(graph[x][i], x, (-sum + value[graph[x][i]] + mod) % mod, depth + 1,
            centroid);
  }
}
void solve(int root) {
  int centroid = findCentroid(root);
  pathSum = 0;
  pathCnt = 0;
  for (int i = 0; i < graph[centroid].size(); i++) {
    if (isCentroid[graph[centroid][i]] == true) continue;
    currCnt = 0;
    currSum = 0;
    DFSLoad(graph[centroid][i], centroid, value[centroid], 2, false);
    cnt[graph[centroid][i]] = currCnt;
    sum[graph[centroid][i]] = currSum;
  }
  for (int i = 0; i < graph[centroid].size(); i++) {
    if (isCentroid[graph[centroid][i]] == true) continue;
    pathCnt -= cnt[graph[centroid][i]];
    pathSum -= sum[graph[centroid][i]];
    pathCnt = (pathCnt + mod) % mod;
    pathSum = (pathSum + mod) % mod;
    DFSCalc(graph[centroid][i], centroid, value[graph[centroid][i]], 2,
            centroid);
    pathCnt += cnt[graph[centroid][i]];
    pathSum += sum[graph[centroid][i]];
    pathCnt = (pathCnt + mod) % mod;
    pathSum = (pathSum + mod) % mod;
  }
  isCentroid[centroid] = true;
  for (int i = 0; i < graph[centroid].size(); i++) {
    if (isCentroid[graph[centroid][i]] == false) {
      solve(graph[centroid][i]);
    }
  }
}
int main() {
  ios::sync_with_stdio(false);
  cin.tie(NULL);
  cin >> n;
  for (int i = 1; i <= n; i++) {
    cin >> value[i];
    value[i] = (value[i] + mod) % mod;
    answer = (answer + value[i]) % mod;
  }
  for (int i = 0; i < n - 1; i++) {
    int u, v;
    cin >> u >> v;
    graph[u].push_back(v);
    graph[v].push_back(u);
  }
  solve(3);
  cout << answer % mod << '\n';
}
