#include <bits/stdc++.h>
#pragma GCC optimize("Ofast")
using namespace std;
template <typename T>
inline void uin(T &a, T b) {
  if (b < a) a = b;
}
template <typename T>
inline void uax(T &a, T b) {
  if (b > a) a = b;
}
const long long maxn = 200 * 1000 + 228, mod = 1000 * 1000 * 1000 + 7;
long long n;
vector<long long> g[maxn];
long long a[maxn], sz[maxn], sm[maxn], left228[maxn], right228[maxn], timer = 0;
inline void add(long long &x, long long y) {
  x += y;
  if (x < 0) x += mod;
  if (x >= mod) x -= mod;
}
inline void men(long long &x, long long y) {
  x -= y;
  if (x < 0) x += mod;
  if (x >= mod) x -= mod;
}
inline long long addi(long long a, long long b) {
  add(a, b);
  return a;
}
void zhfs(long long v, long long par = -1) {
  left228[v] = ++timer;
  sz[v] = 1;
  for (long long to : g[v]) {
    if (to != par) {
      zhfs(to, v);
      sz[v] += sz[to];
    }
  }
  right228[v] = left228[v] + sz[v] - 1;
}
void jfs(long long v, long long sum = 0, long long h = 0, long long par = -1) {
  if (h == 0) {
    add(sum, a[v]);
  } else {
    add(sum, -a[v]);
  }
  sm[v] = sum;
  for (long long to : g[v]) {
    if (to != par) {
      jfs(to, sum, h ^ 1, v);
    }
  }
}
long long var = 0;
long long modif = 1;
long long res = 0;
long long mas[maxn];
void add1(long long l, long long r, long long x) {
  long long kek = (r - l + 1) * x;
  if (kek < 0) kek += 200000LL * mod;
  kek %= mod;
  add(var, kek);
}
void minusravno() {
  var = -var;
  if (var < 0) var += mod;
}
long long get1() { return var; }
void dfs(long long v, long long par = -1) {
  if (par != -1) {
    minusravno();
    add1(left228[v], right228[v], a[par]);
    if (left228[v] > 1) add1(1, left228[v] - 1, a[v]);
    if (right228[v] < n) add1(right228[v] + 1, n, a[v]);
  }
  add(res, get1());
  for (long long to : g[v]) {
    if (to != par) {
      dfs(to, v);
    }
  }
  if (par != -1) {
    add1(left228[v], right228[v], -a[par]);
    if (left228[v] > 1) add1(1, left228[v] - 1, -a[v]);
    if (right228[v] < n) add1(right228[v] + 1, n, -a[v]);
    minusravno();
  }
}
signed main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cin >> n;
  for (long long i = 1; i <= (long long)n; ++i) cin >> a[i];
  for (long long it = 1; it <= (long long)n - 1; ++it) {
    long long u, v;
    cin >> u >> v;
    g[u].push_back(v);
    g[v].push_back(u);
  }
  zhfs(1);
  jfs(1);
  var = 0;
  for (long long i = 1; i <= (long long)n; ++i) {
    add1(left228[i], left228[i], sm[i]);
  }
  dfs(1);
  cout << res % mod << "\n";
  return 0;
}
