#include <bits/stdc++.h>
using namespace std;
int n;
int lab[200005];
vector<vector<int> > a(200005);
int child[200005];
bool dead[200005];
const int mod = 1e9 + 7;
void pdfs(int u, int p) {
  child[u] = 1;
  for (auto v : a[u]) {
    if (v == p || dead[v]) continue;
    pdfs(v, u);
    child[u] += child[v];
  }
}
int findcen(int u, int p, const int total) {
  for (auto v : a[u]) {
    if (v == p || dead[v]) continue;
    if (child[v] > total / 2) return findcen(v, u, total);
  }
  return u;
}
long long curSum[2], preSum[2];
long long ans = 0;
void dfs(int u, int p, int c, const int key, const int root, const int out) {
  curSum[c] = (curSum[c] + lab[u]) % mod;
  if (key == 0)
    ans = (ans +
           (curSum[c] - curSum[c ^ 1] + (1 - c * 2) * lab[root]) * 1LL * out +
           preSum[c] - preSum[c ^ 1]) %
          mod;
  else
    preSum[c] = (preSum[c] + 1LL * (curSum[c] - curSum[c ^ 1]) * key) % mod;
  for (auto v : a[u]) {
    if (v == p || dead[v]) continue;
    dfs(v, u, c ^ 1, key, root, out);
  }
  curSum[c] = (curSum[c] - lab[u]) % mod;
}
void fdfs(int u, int p, int c, int root) {
  curSum[c] = (curSum[c] + lab[u]) % mod;
  ans = (ans + curSum[0] - curSum[1] + lab[root] + curSum[c] - curSum[c ^ 1] +
         (1 - c * 2) * lab[root]) %
        mod;
  for (auto v : a[u]) {
    if (v == p || dead[v]) continue;
    fdfs(v, u, c ^ 1, root);
  }
  curSum[c] = (curSum[c] - lab[u]) % mod;
}
void cal(int u, int phase) {
  int buff = 0;
  if (phase == 0) {
    for (int i = 0; i < a[u].size(); i++) {
      int v = a[u][i];
      if (dead[v]) continue;
      dfs(v, u, 1, 0, u, buff);
      dfs(v, u, 1, 1, u, buff);
      buff += child[v];
    }
  } else {
    for (int i = a[u].size() - 1; i >= 0; i--) {
      int v = a[u][i];
      if (dead[v]) continue;
      dfs(v, u, 1, 0, u, buff);
      dfs(v, u, 1, 1, u, buff);
      buff += child[v];
    }
  }
  memset(curSum, 0, sizeof(curSum));
  memset(preSum, 0, sizeof(preSum));
}
void solve(int u) {
  pdfs(u, u);
  u = findcen(u, u, child[u]);
  pdfs(u, u);
  ans = (ans + lab[u]) % mod;
  dead[u] = true;
  for (auto v : a[u]) {
    if (dead[v]) continue;
    fdfs(v, u, 1, u);
  }
  cal(u, 0);
  cal(u, 1);
  for (auto v : a[u]) {
    if (dead[v]) continue;
    solve(v);
  }
}
signed main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  cin >> n;
  for (int i = 1; i <= n; i++) cin >> lab[i];
  for (int i = 1; i <= n - 1; i++) {
    int u, v;
    cin >> u >> v;
    a[u].push_back(v);
    a[v].push_back(u);
  }
  solve(1);
  ans %= mod;
  while (ans < 0) ans += mod;
  cout << ans << '\n';
}
