#include <bits/stdc++.h>
#pragma GCC optimize("O3")
#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
using namespace std;
template <class T>
inline bool setmin(T &a, T b) {
  if (a > b) return a = b, 1;
  return 0;
}
template <class T>
inline bool setmax(T &a, T b) {
  if (a < b) return a = b, 1;
  return 0;
}
template <class T>
inline T fast(T a, T b, T mod) {
  long long res = 1;
  while (b) {
    if (b & 1) res = (res * a) % mod;
    a = (a * a) % mod;
    b >>= 1;
  }
  return res;
}
template <class T>
istream &operator>>(istream &os, vector<T> &container) {
  for (auto &u : container) os >> u;
  return os;
}
template <class T>
ostream &operator<<(ostream &os, const vector<T> &container) {
  for (auto &u : container) os << u << " ";
  return os;
}
template <class T>
ostream &operator<<(ostream &os, const pair<T, T> &u) {
  os << u.first << " " << u.second << ' ';
  return os;
}
template <class T>
inline T gcd(T a, T b) {
  while (b) swap(a %= b, b);
  return a;
}
const long long INF = 1e9 + 7;
const long long mod = 998244353;
const long long BIG_INF = 1e18;
const long long N = 1e6 + 7;
const long long T = 1 << 20;
const long double inf = 1e18;
long long n, m, q, SZ;
long long centro;
bool blocked[N];
long long koszt[N];
vector<vector<int> > G(N);
long long dfs(int x, int przed = -1) {
  long long roz = 1;
  bool ok = 1;
  for (auto &u : G[x])
    if (u != przed and !blocked[u]) {
      long long temp = dfs(u, x);
      if (temp + temp > SZ) ok = 0;
      roz += temp;
    }
  if (ok and SZ <= roz * 2) centro = x;
  return roz;
}
long long ans = 0;
long long parz = 0;
long long ile_parz = 0;
long long nparz = koszt[centro];
long long ile_nparz = 1;
void dfs2(int u, int gl, long long suma, int przed) {
  suma += koszt[u];
  if (gl & 1)
    ans += (parz + ile_parz * suma) * 2;
  else
    ans += (nparz + ile_nparz * suma) * 2;
  ans %= INF;
  for (auto &v : G[u])
    if (v != przed and !blocked[v]) dfs2(v, gl + 1, -suma, u);
}
void dfs3(int u, int gl, long long suma, int przed) {
  suma += koszt[u];
  if (gl & 1) {
    parz += suma;
    ile_parz++;
  } else {
    nparz += suma;
    ile_nparz++;
  }
  for (auto &v : G[u])
    if (v != przed and !blocked[v]) dfs3(v, gl + 1, -suma, u);
}
void decomp(int x) {
  SZ = dfs(x), dfs(x);
  int centroid = centro;
  blocked[centroid] = true;
  parz = 0;
  ile_parz = 0;
  nparz = koszt[centroid];
  ile_nparz = 1;
  ans += koszt[centro];
  ans %= INF;
  for (auto &u : G[centroid]) {
    if (!blocked[u]) {
      dfs2(u, 1, 0, centroid);
      dfs3(u, 1, -koszt[centroid], centroid);
    }
  }
  for (auto &u : G[centroid])
    if (!blocked[u]) decomp(u);
}
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cin >> n;
  for (int i = 1; i <= n; i++) cin >> koszt[i];
  for (int i = 1; i < n; i++) {
    int a, b;
    cin >> a >> b;
    G[a].push_back(b);
    G[b].push_back(a);
  }
  decomp(1);
  cout << (ans + INF) % INF << '\n';
}
