/* -*- coding: utf-8 -*-
 *
 * 3113.cc:  No.3113 The farthest point - yukicoder
 */

#include<cstdio>
#include<vector>
#include<algorithm>
#include<utility>

using namespace std;

/* constant */

const int MAX_N = 200000;

/* typedef */

using ll = long long;
using pii = pair<int,int>;
using vpii = vector<pii>;

/* global variables */

vpii nbrs[MAX_N];
int ps[MAX_N], pws[MAX_N], cis[MAX_N];
ll xds0[MAX_N], xds1[MAX_N];

/* subroutines */

/* main */

int main() {
  int n;
  scanf("%d", &n);
  for (int i = 1; i < n; i++) {
    int u, v, w;
    scanf("%d%d%d", &u, &v, &w);
    u--, v--;
    nbrs[u].push_back({v, w});
    nbrs[v].push_back({u, w});
  }

  ps[0] = -1, pws[0] = 0;
  ll maxs = 0;
  for (int u = 0; u >= 0;) {
    auto &nbru = nbrs[u];
    int up = ps[u];

    if (cis[u] < nbru.size()) {
      auto [v, w] = nbru[cis[u]++];
      if (v != up) {
	ps[v] = u, pws[v] = w;
	u = v;
      }
    }
    else {
      maxs = max(maxs, xds0[u] + xds1[u]);

      if (up >= 0) {
	ll ud = xds0[u] + pws[u];
	if (ud > 0) {
	  if (xds0[up] < ud) xds1[up] = xds0[up], xds0[up] = ud;
	  else if (xds1[up] < ud) xds1[up] = ud;
	}
      }
      
      u = up;
    }

  }

  printf("%lld\n", maxs);
  
  return 0;
}