#include <bits/stdc++.h>
using namespace std;
template <typename T>
ostream& operator<<(ostream& s, vector<T> const& v) {
  s << '{';
  for (int i = 0; i < int(v.size()); i++) s << (i ? "," : "") << v[i];
  return s << '}';
}
template <typename S, typename T>
ostream& operator<<(ostream& s, pair<S, T> const& p) {
  return s << '(' << p.first << ',' << p.second << ')';
}
struct Vtx {
  int V;
  long long alt, sOdd, nOdd, sEven, nEven;
} vtxs[200000];
int N;
vector<vector<int> > adj;
constexpr long long MOD = 1000000007;
inline void addMod(long long& a, long long b) {
  a = ((a % MOD + b % MOD) % MOD + MOD) % MOD;
}
void dfs(int n, int p) {
  auto& v = vtxs[n];
  addMod(v.sOdd, v.V);
  addMod(v.nOdd, 1);
  addMod(v.alt, v.V);
  long long tnEven = 0, tnOdd = 0;
  for (int m : adj[n])
    if (m != p) {
      dfs(m, n);
      auto& v2 = vtxs[m];
      addMod(v.nOdd, v2.nEven);
      addMod(v.sOdd, v2.sEven);
      addMod(v.sOdd, v2.nEven * v.V);
      addMod(v.nEven, v2.nOdd);
      addMod(v.sEven, v2.sOdd);
      addMod(v.sEven, -v2.nOdd * v.V);
      addMod(v.alt, v2.alt);
      addMod(tnEven, v2.nEven);
      addMod(tnOdd, v2.nOdd);
    }
  long long oddPaths = 0, evenPaths = 0;
  for (int m : adj[n])
    if (m != p) {
      auto& v2 = vtxs[m];
      long long otherOdd = (tnOdd - v2.nOdd) % MOD;
      addMod(v.alt, 2 * v2.sOdd * otherOdd);
      addMod(oddPaths, v2.nOdd * otherOdd);
      long long otherEven = (tnEven - v2.nEven) % MOD;
      addMod(v.alt, 2 * v2.sEven * (otherEven + 1));
      addMod(evenPaths, v2.nEven * (otherEven + 2));
    }
  addMod(v.alt, -v.V * oddPaths);
  addMod(v.alt, v.V * evenPaths);
}
int main() {
  scanf("%d", &N);
  adj.resize(N);
  for (int n = 0; n < int(N); n++) scanf("%d", &vtxs[n].V);
  for (int a = 0; a < int(N - 1); a++) {
    int u, v;
    scanf("%d%d", &u, &v);
    --u;
    --v;
    adj[u].push_back(v);
    adj[v].push_back(u);
  }
  dfs(0, -1);
  printf("%d\n", int(vtxs[0].alt));
}
