#include <bits/stdc++.h>
using namespace std;
const long long MAXN = 4e5 + 100;
const long long MOD = 1e9 + 7;
struct Edge {
  long long from, to, nxt;
} edge[MAXN];
long long eidx;
long long head[MAXN];
void addedge(long long from, long long to) {
  edge[eidx].from = from;
  edge[eidx].to = to;
  edge[eidx].nxt = head[from];
  head[from] = eidx++;
}
void einit() {
  eidx = 0;
  memset(head, -1, sizeof head);
}
long long val[MAXN];
long long o[MAXN], e[MAXN], lev[MAXN];
long long ans;
bool vis[MAXN];
void dfs(long long u, long long h, long long fa) {
  lev[u] = h;
  vis[u] = 1;
  o[u] = e[u] = 0;
  for (long long i = head[u]; i != -1; i = edge[i].nxt) {
    long long v = edge[i].to;
    if (vis[v]) continue;
    dfs(v, h + 1, u);
    long long ta =
        2 * (o[u] * e[v] % MOD - o[v] * e[u] % MOD) % MOD * val[u] % MOD;
    ta = (ta % MOD + MOD) % MOD;
    if (u == 1) {
    }
    ans = (ans + ta) % MOD;
    o[u] += e[v];
    e[u] += o[v];
  }
  o[u]++;
}
void init() { memset(vis, 0, sizeof vis); }
int main() {
  long long n;
  {
    cin >> n;
    einit();
    init();
    for (int i = 1; i <= n; ++i) {
      scanf("%lld", &val[i]);
    }
    for (int i = 1; i < n; ++i) {
      long long p1, p2;
      scanf("%lld%lld", &p1, &p2);
      addedge(p1, p2);
      addedge(p2, p1);
    }
    ans = 0;
    dfs(1, 1, -1);
    for (int i = 1; i <= n; ++i) {
      long long upo, upe, ta;
      if (lev[i] % 2) {
        upo = o[1] - o[i] + 1;
        upe = e[1] - e[i];
      } else {
        upo = e[1] - o[i] + 1;
        upe = o[1] - e[i];
      }
      ta = 2 * (upo * o[i] % MOD - upe * e[i] % MOD) % MOD * val[i] % MOD;
      ta -= val[i];
      ta = (ta % MOD + MOD) % MOD;
      ans = (ans + ta) % MOD;
    }
    cout << ans << endl;
  }
  return 0;
}
