#include<bits/stdc++.h>
#define fi first
#define se second
#define endl "\n"
#define ii pair<int, int>
using namespace std;

const int N = 3e5 + 10, mod = 1e9 + 7;

int st[N], ed[N], rev_st[N], dd[N], cnt[2], sz[N], cost[N];

int pref[2][N << 2], suff[2][N << 2], g[N << 2], sum[N << 2];

vector<pair<int, int> > adj[N];

int timer, n;

long long ans;

void up(int s, int l, int r, int pos, int val) {
  if (l == r) {
    pref[0][s] = pref[1][s] = suff[0][s] = suff[1][s] = 0;
    pref[val][s] = suff[val][s] = 1;
//    sum[s] = 0;
    sum[s] = 1;
    g[s] = val;
    return;
  }
  int mid = l + r >> 1;
  if (pos <= mid) up(s << 1, l, mid, pos, val);
  else up(s << 1 | 1, mid + 1, r, pos, val);
  g[s] = g[s << 1] + g[s << 1 | 1];
  sum[s] = (sum[s << 1] + sum[s << 1 | 1]) % mod;
  for(int j = 0; j < 2; j++) {
    pref[j][s] = pref[j][s << 1];
//    if (pos == n - 1) {
//      cout << sum[s << 1] <<
//    }
    if (g[s << 1] == (mid - l + 1) * j) pref[j][s] += pref[j][s << 1 | 1];
    suff[j][s] = suff[j][s << 1 | 1];
    if (g[s << 1 | 1] == (r - mid) * j) suff[j][s] += suff[j][s << 1];
    sum[s] = (sum[s] + 1LL * suff[j][s << 1] * pref[j][s << 1 | 1] % mod) % mod;
  }
//  if (pos == n - 1) cout << sum[s] << " " << l << " " << r << endl;
}

void prep (int u, int p) {
//  cout << u << endl;
  st[u] = ++timer;
  rev_st[timer] = u;
  sz[u] = 1;
  for(auto &[v, c] : adj[u]) if (v != p) {
    cost[v] = c;
    prep(v, u);
    sz[u] += sz[v];
  }
  ed[u] = timer;
}

void dfs(int u, int p) {
  int heavy = 0;
//  cout << u << endl;
  for(auto &[v, w] : adj[u]) if (v != p && sz[v] > sz[heavy]) heavy = v;
  for(auto &[v, w] : adj[u]) if (v != p && v != heavy) {
    dfs(v, u);
    for(int j = st[v]; j <= ed[v]; j++) {
      up(1, 0, n - 1, rev_st[j], 0);
    }
  }
  if (heavy) dfs(heavy, u);
//  dd[u] = 1;
  up(1, 0, n - 1, u, 1);
  for(auto &[v, w] : adj[u]) if (v != p && v != heavy) {
    for(int j = st[v]; j <= ed[v]; j++) {
      up(1, 0, n - 1, rev_st[j], 1);
    }
  }

  int ways = (1LL * n * (n + 1) / 2 % mod - sum[1] + mod) % mod * cost[u] % mod;

  ans += ways;
  ans %= mod;

//  for(int l = 0; l < n; l++) {
//    cnt[0] = cnt[1] = 0;
//    for(int r = l; r < n; r++) {
//      cnt[dd[r]] = 1;
//      if (cnt[0] && cnt[1]) {
//        ans += cost[u];
//        ans %= mod;
//      }
//    }
//  }
}

int maintenance_costs_sum (vector<int> U, vector<int> V, vector<int> W) {
//  n = 5;
  n = U.size() + 1;
  for(int i = 0; i < n; i++) up(1, 0, n - 1, i, 0);

  for(int i = 0; i < n - 1; i++) {
    adj[U[i]].emplace_back(V[i], W[i]);
    adj[V[i]].emplace_back(U[i], W[i]);
  }

  prep(0, 0);

  dfs(0, 0);

  return ans;
}

#ifdef ngu
int main() {

  freopen ("task.inp", "r", stdin);
  freopen ("task.out", "w", stdout);

  int tot = maintenance_costs_sum({0, 2, 2, 0}, {2, 1, 4, 3}, {2, 1, 1, 1});
  cout << tot << endl;
}
#endif // ngu