#include <bits/stdc++.h>
#pragma GCC optimize(2)
#pragma GCC optimize(3)
#pragma GCC optimize("Ofast")
#pragma GCC optimize("inline")
#pragma GCC optimize("-fgcse")
#pragma GCC optimize("-fgcse-lm")
#pragma GCC optimize("-fipa-sra")
#pragma GCC optimize("-ftree-pre")
#pragma GCC optimize("-ftree-vrp")
#pragma GCC optimize("-fpeephole2")
#pragma GCC optimize("-ffast-math")
#pragma GCC optimize("-fsched-spec")
#pragma GCC optimize("unroll-loops")
#pragma GCC optimize("-falign-jumps")
#pragma GCC optimize("-falign-loops")
#pragma GCC optimize("-falign-labels")
#pragma GCC optimize("-fdevirtualize")
#pragma GCC optimize("-fcaller-saves")
#pragma GCC optimize("-fcrossjumping")
#pragma GCC optimize("-fthread-jumps")
#pragma GCC optimize("-funroll-loops")
#pragma GCC optimize("-fwhole-program")
#pragma GCC optimize("-freorder-blocks")
#pragma GCC optimize("-fschedule-insns")
#pragma GCC optimize("inline-functions")
#pragma GCC optimize("-ftree-tail-merge")
#pragma GCC optimize("-fschedule-insns2")
#pragma GCC optimize("-fstrict-aliasing")
#pragma GCC optimize("-fstrict-overflow")
#pragma GCC optimize("-falign-functions")
#pragma GCC optimize("-fcse-skip-blocks")
#pragma GCC optimize("-fcse-follow-jumps")
#pragma GCC optimize("-fsched-interblock")
#pragma GCC optimize("-fpartial-inlining")
#pragma GCC optimize("no-stack-protector")
#pragma GCC optimize("-freorder-functions")
#pragma GCC optimize("-findirect-inlining")
#pragma GCC optimize("-fhoist-adjacent-loads")
#pragma GCC optimize("-frerun-cse-after-loop")
#pragma GCC optimize("inline-small-functions")
#pragma GCC optimize("-finline-small-functions")
#pragma GCC optimize("-ftree-switch-conversion")
#pragma GCC optimize("-foptimize-sibling-calls")
#pragma GCC optimize("-fexpensive-optimizations")
#pragma GCC optimize("-funsafe-loop-optimizations")
#pragma GCC optimize("inline-functions-called-once")
#pragma GCC optimize("-fdelete-null-pointer-checks")
using namespace std;
const long long mo = 1e9 + 7;
template <typename _T>
void read(_T &x) {
  _T f = 1;
  x = 0;
  char s = getchar();
  while (s > '9' || s < '0') {
    if (s == '-') f = -1;
    s = getchar();
  }
  while (s >= '0' && s <= '9') {
    x = (x << 3) + (x << 1) + (s ^ 48);
    s = getchar();
  }
  x *= f;
}
long long sum1[200005], sum2[200005], ans, val[200005];
long long siz[200005], sup1[200005], sup2[200005];
int head[200005], tot, dep[200005], n, id[200005], f[200005];
struct edge {
  int v, nxt;
} e[200005 << 1];
bool cmp(int a, int b) { return dep[a] < dep[b]; }
void addEdge(int u, int v) {
  e[++tot] = (edge){v, head[u]};
  head[u] = tot;
}
void dfs(int u, int fa) {
  f[u] = fa;
  dep[u] = dep[fa] + 1;
  sum1[u]++;
  siz[u]++;
  for (int i = head[u]; i; i = e[i].nxt) {
    int v = e[i].v;
    if (v == fa) continue;
    dfs(v, u);
    sum1[u] += sum2[v];
    sum2[u] += sum1[v];
    siz[u] += siz[v];
  }
  for (int i = head[u]; i; i = e[i].nxt) {
    int v = e[i].v;
    if (v == fa) continue;
    (ans +=
     (sum2[v] - sum1[v]) % mo * (siz[u] - siz[v] - 1) % mo * val[u] % mo) %= mo;
  }
  (ans += (siz[u] - 1) * val[u] % mo) %= mo;
  (ans += (sum1[u] - sum2[u]) % mo * (n - siz[u] + 1) % mo * val[u] % mo) %= mo;
}
signed main() {
  read(n);
  for (int i = 1; i <= n; i++)
    read(val[i]), val[i] = (val[i] + mo) % mo, id[i] = i;
  for (int i = 1; i < n; i++) {
    int u, v;
    read(u);
    read(v);
    addEdge(u, v);
    addEdge(v, u);
  }
  dfs(1, 0);
  sort(id + 1, id + n + 1, cmp);
  for (int i = 2; i <= n; i++) {
    int u = id[i];
    sup1[u] = sup2[f[u]] + sum2[f[u]] - sum1[u];
    sup2[u] = sup1[f[u]] + sum1[f[u]] - sum2[u];
    (ans += (sup1[u] - sup2[u]) % mo * siz[u] % mo * val[u] % mo) %= mo;
  }
  printf("%lld\n", (ans + mo) % mo);
  return 0;
}
