#include <bits/stdc++.h>
using namespace std;
const long double EPS = 1e-9;
const long double PI = acos(-1);
const int N = 2e5 + 5;
const int MOD = 1e9 + 7;
const int INF = 0x3f3f3f3f;
long long n, o[N], e[N], vis[N], par[N];
map<pair<int, int>, long long> ee, oo;
long long sz[N];
long long v[N];
long long ans;
vector<int> adj[N];
pair<int, int> dfs(int u) {
  vis[u] = 1;
  for (int v : adj[u])
    if (!vis[v]) {
      par[v] = u;
      pair<int, int> p = dfs(v);
      e[u] = p.second + e[u];
      o[u] = p.first + o[u];
      ee[make_pair(u, v)] = o[v];
      oo[make_pair(u, v)] = e[v];
    }
  o[u]++;
  return {e[u], o[u]};
}
void dfs_p(int u, int p) {
  if (p) {
    ee[make_pair(u, p)] = o[p] - e[u];
    oo[make_pair(u, p)] = e[p] - o[u];
    o[u] += oo[make_pair(u, p)];
    e[u] += ee[make_pair(u, p)];
  }
  vis[u] = 1;
  for (int v : adj[u])
    if (!vis[v]) {
      dfs_p(v, u);
    }
}
long long dfs_t(int u) {
  vis[u] = 1;
  for (int v : adj[u])
    if (!vis[v]) {
      sz[u] += dfs_t(v);
    }
  sz[u]++;
  return sz[u];
}
int main() {
  scanf("%lld", &n);
  for (int i = 1; i <= n; i++) scanf("%lld", &v[i]);
  for (int i = 1; i < n; i++) {
    int u, v;
    scanf("%d %d", &u, &v);
    adj[u].push_back(v);
    adj[v].push_back(u);
  }
  dfs(1);
  memset(vis, 0, sizeof vis);
  dfs_p(1, 0);
  memset(vis, 0, sizeof vis);
  dfs_t(1);
  for (int i = 1; i <= n; i++) {
    ans = (ans + (n * v[i])) % MOD;
    long long ev = 0;
    long long od = 0;
    for (int j : adj[i]) {
      long long qt = par[j] == i ? n - sz[j] : sz[i];
      long long todd = ((oo[make_pair(i, j)] * qt) % MOD);
      long long teven = ((ee[make_pair(i, j)] * qt) % MOD);
      ev = (ev + teven) % MOD;
      od = (od + todd) % MOD;
    }
    ans = (ans - ((ev * v[i]) % MOD) + MOD) % MOD;
    ans = (ans + ((od * v[i]) % MOD) + MOD) % MOD;
  }
  printf("%lld\n", ans);
  return 0;
}
