#include <bits/stdc++.h>
using namespace std;
const long long N = 200000 + 5;
const long long MOD = 1000000007;
long long add(long long a, long long b) {
  a += b;
  a %= MOD;
  a += MOD;
  a %= MOD;
  return a;
}
long long mul(long long a, long long b) { return a * (long long)b % MOD; }
long long n;
long long v[N];
vector<long long> g[N];
long long dp[2][2][N];
long long cnt[2][2][N];
bool viz[N];
long long ans = 0;
long long tot[2][2];
long long tcn[2][2];
long long gt(long long nod, long long sgn, long long cnt1, long long s1,
             long long cnt2, long long s2) {
  long long ans = mul(s2, cnt1);
  ans = add(ans, mul(s1, cnt2));
  if (sgn == 0) {
    ans = add(ans, -mul(cnt1, mul(cnt2, v[nod])));
  } else {
    ans = add(ans, mul(cnt1, mul(cnt2, v[nod])));
  }
  return ans;
}
long long sub[N];
void dfs(long long nod) {
  sub[nod] = v[nod];
  viz[nod] = 1;
  dp[0][0][nod] = -v[nod];
  dp[1][1][nod] = v[nod];
  cnt[0][0][nod] = 1;
  cnt[1][1][nod] = 1;
  long long dad = -1;
  for (auto &nou : g[nod]) {
    if (viz[nou]) {
      dad = nou;
      continue;
    }
    sub[nod] += sub[nou];
    dfs(nou);
    for (long long st = 0; st < 2; st++) {
      for (long long now = 0; now < 2; now++) {
        cnt[st][now][nod] = add(cnt[st][now][nod], cnt[st][1 - now][nou]);
        if (now == 0) {
          dp[st][now][nod] =
              add(dp[st][now][nod], -mul(v[nod], cnt[st][1 - now][nou]));
        } else {
          dp[st][now][nod] =
              add(dp[st][now][nod], mul(v[nod], cnt[st][1 - now][nou]));
        }
        dp[st][now][nod] = add(dp[st][now][nod], dp[st][1 - now][nou]);
        if (nod == 1 && st == 1 && now == 1) {
        }
      }
    }
  }
  for (long long i = 0; i < 2; i++)
    for (long long j = 0; j < 2; j++) tot[i][j] = tcn[i][j] = 0;
  for (auto &nou : g[nod]) {
    if (nou == dad) continue;
    for (long long i = 0; i < 2; i++) {
      for (long long j = 0; j < 2; j++) {
        tot[i][j] = add(tot[i][j], dp[i][j][nou]);
        tcn[i][j] = add(tcn[i][j], cnt[i][j][nou]);
      }
    }
  }
  long long acum = 0;
  for (auto &nou : g[nod]) {
    if (nou == dad) continue;
    for (long long i = 0; i < 2; i++) {
      for (long long j = 0; j < 2; j++) {
        tot[i][j] = add(tot[i][j], -dp[i][j][nou]);
        tcn[i][j] = add(tcn[i][j], -cnt[i][j][nou]);
      }
    }
    for (long long now = 0; now < 2; now++) {
      long long cur1 = gt(nod, now, cnt[1][1 - now][nou], dp[1][1 - now][nou],
                          tcn[0][1 - now], tot[0][1 - now]);
      long long cur2 = gt(nod, now, cnt[1][1 - now][nou], dp[1][1 - now][nou],
                          tcn[1][1 - now], tot[1][1 - now]);
      acum = add(acum, cur1);
      acum = add(acum, cur2);
    }
    for (long long i = 0; i < 2; i++) {
      for (long long j = 0; j < 2; j++) {
        tot[i][j] = add(tot[i][j], dp[i][j][nou]);
        tcn[i][j] = add(tcn[i][j], cnt[i][j][nou]);
      }
    }
  }
  ans = add(ans, acum);
  long long fini = 0;
  fini = add(fini, dp[1][1][nod]);
  fini = add(fini, dp[1][1][nod]);
  fini = add(fini, -sub[nod]);
  ans = add(ans, fini);
  return;
  return;
  cout << nod << " : " << dp[1][1][nod] << " " << dp[1][0][nod] << "\n";
  cout << nod << " : " << dp[0][1][nod] << " " << dp[0][0][nod] << "\n\n\n";
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  cin >> n;
  for (long long i = 1; i <= n; i++) {
    cin >> v[i];
  }
  for (long long i = 1; i < n; i++) {
    long long a, b;
    cin >> a >> b;
    g[a].push_back(b);
    g[b].push_back(a);
  }
  dfs(1);
  cout << ans << "\n";
  return 0;
}
