#include <bits/stdc++.h>
using namespace std;
const int kMod = 1e9 + 7;
const int kNmax = 2e5 + 10;
int n, v[kNmax], sub[kNmax], up[kNmax][2], down[kNmax][2], res, res_even;
vector<int> g[kNmax];
void dfs(int node, int father = 0) {
  sub[node] = 1;
  down[node][0] = 1;
  int ways = (1LL * n * n) % kMod;
  for (int vec : g[node]) {
    if (vec == father) continue;
    dfs(vec, node);
    ways = (ways - 1LL * sub[vec] * sub[vec]) % kMod;
    if (ways < 0) ways += kMod;
    sub[node] += sub[vec];
    down[node][0] += down[vec][1];
    down[node][1] += down[vec][0];
  }
  ways = (ways - 1LL * (n - sub[node]) * (n - sub[node])) % kMod;
  if (ways < 0) ways += kMod;
  res = (res + 1LL * ways * v[node]) % kMod;
  if (res < 0) res += kMod;
}
void dfs_bad(int node, int father = 0) {
  int s0 = 0, s1 = 0;
  int ways = (1LL * down[node][1] * (n - sub[node])) % kMod;
  ways = (ways + 1LL * up[node][1] * sub[node]) % kMod;
  for (int vec : g[node]) {
    if (vec == father) continue;
    ways = (ways + 1LL * down[vec][0] * (sub[node] - sub[vec])) % kMod;
    s0 += down[vec][0];
    s1 += down[vec][1];
  }
  res_even = (res_even + 1LL * ways * v[node]) % kMod;
  if (res_even < 0) res_even += kMod;
  for (int vec : g[node]) {
    if (vec == father) continue;
    up[vec][0] = up[node][1] + s0 - down[vec][0];
    up[vec][1] = n - sub[vec] - up[vec][0];
    dfs_bad(vec, node);
  }
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(nullptr);
  cin >> n;
  for (int i = 1; i <= n; i++) cin >> v[i];
  for (int i = 1, a, b; i < n; i++) {
    cin >> a >> b;
    g[a].push_back(b);
    g[b].push_back(a);
  }
  dfs(1);
  up[1][0] = 1;
  dfs_bad(1);
  res = (res - 2LL * res_even) % kMod;
  if (res < 0) res += kMod;
  cout << res;
}
