#include <bits/stdc++.h>
using namespace std;
void Rd(int &x) {
  static char c;
  x = 0;
  while ((c = getchar()) < 48)
    ;
  do x = (x << 3) + (x << 1) + (c ^ 48);
  while ((c = getchar()) > 47);
}
int n;
int Next[200004 << 1], V[200004 << 1], W[200004], Head[200004], tot;
void Add_Edge(int u, int v) { Next[++tot] = Head[u], V[Head[u] = tot] = v; }
int Sz[200004], G, Mn, Nowsz;
bool Mark[200004];
long long Ans, Dis[200004];
void GetG(int x, int f) {
  int y, mx = 0;
  Sz[x] = 1;
  for (int i = Head[x]; i; i = Next[i])
    if (!Mark[y = V[i]] && y != f) {
      GetG(y, x);
      Sz[x] += Sz[y];
      mx = max(mx, Sz[y]);
    }
  mx = max(mx, Nowsz - Sz[x]);
  if (mx < Mn) Mn = mx, G = x;
}
int m;
struct Node {
  int l;
  long long d;
} D[200004];
long long Calc(int x) {
  long long Tmp[2] = {0, 0}, Cnt[2] = {0, 0}, Res = 0;
  for (int i = (0), i_end_ = (m); i < i_end_; ++i)
    (Tmp[D[i].l & 1] += D[i].d) %= 1000000007, Cnt[D[i].l & 1]++;
  Res -= 2 * Cnt[1] * Tmp[1] + Cnt[1] * Cnt[1] % 1000000007 * W[x];
  Res += 2 * Cnt[0] * Tmp[0] + Cnt[0] * Cnt[0] % 1000000007 * W[x];
  return Res % 1000000007;
}
void Gets(int x, int f, int d) {
  D[m++] = (Node){d, Dis[x]};
  int y;
  Sz[x] = 1;
  for (int i = Head[x]; i; i = Next[i])
    if (!Mark[y = V[i]] && y != f) {
      Dis[y] = Dis[x] + ((d & 1) ? W[y] : -W[y]);
      Gets(y, x, d + 1);
      Sz[x] += Sz[y];
    }
}
void Work(int x, int sz) {
  Mn = 200004, Nowsz = sz;
  GetG(x, 0);
  Mark[x = G] = 1;
  m = Dis[x] = 0;
  Gets(x, 0, 0);
  Ans += Calc(x);
  if (sz == 1) return;
  int y;
  for (int i = Head[x]; i; i = Next[i])
    if (!Mark[y = V[i]]) {
      m = 0;
      Gets(y, x, 1);
      Ans -= Calc(x);
      Work(y, Sz[y]);
    }
}
int main() {
  Rd(n);
  for (int i = (1), i_end_ = (n + 1); i < i_end_; ++i) scanf("%d", &W[i]);
  for (int i = (1), i_end_ = (n); i < i_end_; ++i) {
    int u, v, w;
    Rd(u), Rd(v);
    Add_Edge(u, v);
    Add_Edge(v, u);
  }
  Work(1, n);
  printf("%I64d\n", (Ans % 1000000007 + 1000000007) % 1000000007);
  return 0;
}
