#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;

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

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

int timer, n;

long long ans;

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++) {
      dd[rev_st[j]] = 0;
//      if (u == 2) cout << rev_st[j] << endl;
    }
  }
  if (heavy) dfs(heavy, u);
  dd[u] = 1;
  for(auto &[v, w] : adj[u]) if (v != p && v != heavy) {
    for(int j = st[v]; j <= ed[v]; j++) dd[rev_st[j]] = 1;
  }
//  if (u == 2) {
//    for(int i = 0; i < n; i++) cout << dd[i] << " "; cout << endl;
//    cout << u << endl;
////  }
  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];
//        cout << l << " " << r << " " << u << " " << cost[u] << endl;
      }
    }
  }
}

int maintenance_costs_sum (vector<int> U, vector<int> V, vector<int> W) {
  n = U.size() + 1;
  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