#include <bits/stdc++.h>
using namespace std;
const int maxn = 200005;
const long long mod = 1e9 + 7;
long long n, val[maxn], siz[maxn], root, head[maxn], cnt, vis[maxn], son[maxn],
    ans, ji, ou, nowji, nowou, dis[maxn], mx, tot[2], sum[2];
struct edge {
  long long to, v, next;
} e[maxn << 1];
void add(long long a, long long b) {
  e[cnt].to = b;
  e[cnt].next = head[a];
  head[a] = cnt++;
}
void getroot(long long u, long long pre) {
  siz[u] = 1;
  son[u] = 0;
  for (long long i = head[u]; i; i = e[i].next) {
    if (vis[e[i].to] || e[i].to == pre) continue;
    getroot(e[i].to, u);
    siz[u] += siz[e[i].to];
    son[u] = max(son[u], siz[e[i].to]);
  }
  son[u] = max(son[u], mx - siz[u]);
  if (son[u] < son[root]) root = u;
}
void getans(long long u, long long pre, long long o) {
  dis[u] = -dis[pre] + val[u];
  dis[u] = (dis[u] + mod) % mod;
  if (o == 1) {
    ans = (ans + dis[u] * 2 % mod) % mod;
    ans =
        (ans + 2 * ((sum[1] % mod + tot[1] * dis[u] % mod) % mod) % mod) % mod;
  } else {
    ans =
        (ans + 2 * ((sum[0] % mod + tot[0] * dis[u] % mod) % mod) % mod) % mod;
  }
  for (long long i = head[u]; i; i = e[i].next) {
    if (e[i].to == pre || vis[e[i].to]) continue;
    getans(e[i].to, u, o ^ 1);
  }
}
void getdis(long long u, long long pre, long long o) {
  dis[u] = -dis[pre] + val[u];
  dis[u] = (dis[u] % mod + mod) % mod;
  tot[o]++;
  if (tot[o] >= mod) tot[o] -= mod;
  sum[o] = (sum[o] + dis[u]) % mod;
  for (long long i = head[u]; i; i = e[i].next) {
    if (e[i].to == pre || vis[e[i].to]) continue;
    getdis(e[i].to, u, o ^ 1);
  }
}
void calc(long long u) {
  tot[0] = tot[1] = sum[0] = sum[1] = 0;
  for (long long i = head[u]; i; i = e[i].next) {
    if (vis[e[i].to]) continue;
    dis[u] = val[u];
    getans(e[i].to, u, 0);
    dis[u] = 0;
    getdis(e[i].to, u, 0);
  }
  ans = (ans + val[u]) % mod;
}
void dfs(long long u) {
  vis[u] = 1;
  calc(u);
  for (long long i = head[u]; i; i = e[i].next) {
    if (vis[e[i].to]) continue;
    root = 0;
    mx = siz[e[i].to];
    getroot(e[i].to, 0);
    dfs(root);
  }
}
int main() {
  scanf("%lld", &n);
  long long a, b, c;
  ans = 0;
  cnt = 1;
  for (long long i = 1; i <= n; ++i)
    scanf("%lld", &val[i]), val[i] = (val[i] % mod + mod) % mod;
  for (long long i = 1; i < n; ++i) {
    scanf("%lld%lld", &a, &b);
    add(a, b);
    add(b, a);
  }
  root = 0;
  siz[0] = son[0] = mx = n + 1;
  getroot(1, 0);
  dfs(root);
  printf("%lld\n", (ans % mod + mod) % mod);
}
