#include <cstdio>

 #include <cmath>

 #include <cstring>

 #include <algorithm>

 using namespace std;

 #define N 1000010

 struct Edge {

     int v, w, nxt;

 } edge[N*];

 int head[N], tot, cur[N]; long long sz[N];

 void Add(int u, int v, int w) {

     edge[tot] = (Edge) {v, w, head[u]}; head[u] = tot++;

     edge[tot] = (Edge) {u, w, head[v]}; head[v] = tot++;

 }

 void DFS(int u, int fa) {

     sz[u] = ;

     for(int i = head[u]; ~i; i = edge[i].nxt) {

         int v = edge[i].v;

         if(v == fa) continue;

         cur[v] = i;

         DFS(v, u);

         sz[u] += sz[v];

     }

 }

 int main() {

     int n;

     while(~scanf("%d", &n)) {

         tot = ;

         memset(head, -, sizeof(head));

         memset(sz, , sizeof(sz));

         for(int i = ; i < n; i++) {

             int u, v, w;

             scanf("%d%d%d", &u, &v, &w);

             Add(u, v, w);

         }

         DFS(, -);

         long long ans = ;

         for(int i = ; i <= n; i++) {

             ans += (long long)edge[cur[i]].w * abs(n - sz[i] - sz[i]);

         }

         printf("%lld\n", ans);

     }

     return ;

 }