#include <bits/stdc++.h>
using namespace std;
const int MOD = 1e9 + 7;
void add(int &x, int y) {
  x += y;
  if (x >= MOD) x -= MOD;
  if (x < 0) x += MOD;
}
int _add(int x, int y) {
  x += y;
  if (x >= MOD) x -= MOD;
  if (x < 0) x += MOD;
  return x;
}
int mul(int a, int b) { return (a * 1LL * b) % MOD; }
const int N = 200010;
int ans = 0;
int a[N];
int sz[N][2], dp[N][2];
vector<int> edges[N];
void dfs(int v, int p = -1) {
  for (int iter = 0; iter < 2; iter++) {
    sz[v][0] = 0;
    sz[v][1] = 0;
    dp[v][0] = 0;
    dp[v][1] = 0;
    int sum_odd = 0, sum_even = 0;
    for (int u : edges[v]) {
      if (u == p) continue;
      if (iter == 0) dfs(u, v);
      if (sz[u][1]) {
        add(ans, mul(dp[u][1], sz[v][0] + sz[v][1]));
        add(ans, mul(MOD - a[v], mul(sz[u][1], sz[v][0] + sz[v][1])));
        add(ans, mul(sum_odd, sz[u][1]));
        add(ans, mul(MOD - sum_even, sz[u][1]));
      }
      if (sz[u][0]) {
        add(ans, mul(dp[u][0], sz[v][0] + sz[v][1]));
        add(ans, mul(a[v], mul(sz[u][0], sz[v][0] + sz[v][1])));
        add(ans, mul(MOD - sum_odd, sz[u][0]));
        add(ans, mul(sum_even, sz[u][0]));
      }
      sz[v][0] += sz[u][1];
      sz[v][1] += sz[u][0];
      add(dp[v][0], _add(dp[u][1], mul(sz[u][1], MOD - a[v])));
      add(dp[v][1], _add(dp[u][0], mul(sz[u][0], a[v])));
      add(sum_odd, dp[u][1]);
      add(sum_even, dp[u][0]);
    }
    reverse((edges[v]).begin(), (edges[v]).end());
  }
  add(ans, mul(2, dp[v][1]));
  sz[v][1]++;
  add(dp[v][1], a[v]);
  add(ans, a[v]);
}
void solve() {
  int n;
  cin >> n;
  for (int i = 1; i <= n; i++) {
    cin >> a[i];
    if (a[i] < 0) a[i] += MOD;
  }
  for (int i = 0; i < n - 1; i++) {
    int v, u;
    cin >> v >> u;
    edges[v].push_back(u);
    edges[u].push_back(v);
  }
  dfs(1);
  cout << ans << "\n";
}
int main() {
  ios::sync_with_stdio(NULL), cin.tie(0), cout.tie(0);
  cout.setf(ios::fixed), cout.precision(20);
  solve();
}
