#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for(int i=0; i<n; i++)
#define debug 0
#define YES cout << "Yes" << endl;
#define NO cout << "No" << endl;
using ll = long long;
using ld = long double;
const int mod = 998244353;
const int MOD = 1000000007;
const double pi = atan2(0, -1);
const int inf = 1 << 31 - 1;
const ll INF = 1LL << 63-1;
#include <time.h>
#include <chrono>
//vectorの中身を空白区切りで出力
template<typename T> 
void print1(vector<T> v) {
	for (int i = 0; i < v.size(); i++) {
		cout << v[i];
		if (i < v.size() - 1) {
			cout << " ";
		}
	}
}

//vectorの中身を改行区切りで出力
template<typename T>
void print2(vector<T> v) {
	for (auto x : v) {
		cout << x << endl;
	}
}

//二次元配列を出力
template<typename T>
void printvv(vector<vector<T>> vv) {
	for (vector<T> v : vv) {
		print1(v);
		cout << endl;
	}
}

//vectorを降順にソート
template<typename T>
void rsort(vector<T> &v) {
	sort(v.begin(), v.end());
	reverse(v.begin(), v.end());
}

//昇順priority_queueを召喚
template<typename T>
struct rpriority_queue {
	priority_queue<T, vector<T>, greater<T>> pq;

	void push(T x) {
		pq.push(x);
	}

	void pop() {
		pq.pop();
	}

	T top() {
		return pq.top();
	}

	size_t size() {
		return pq.size();
	}

	bool empty() {
		return pq.empty();
	}
};


//高速10^n計算(mod mod)
ll tenth(int n) {
	if (n == 0) {
		return 1;
	}
	else if (n % 2 == 0) {
		ll x = tenth(n / 2);
		x %= mod;
		x *= x;
		x %= mod;
		return x;
	}
	else {
		ll x = tenth(n - 1);
		x *= 10;
		x %= mod;
		return x;
	}
}


//高速a^n計算
ll power(int a, int n){
	if(n == 0){
		return 1;
	}
	else if(n % 2 == 0){
		ll x = power(a, n / 2);
		x *= x;
		return x;
	}
	else {
		ll x = power(a, n - 1);
		x *= a;
		return x;
	}
}


//n以下の素数列を生成
vector<int> prime (int n) {
	vector<bool> ch(n, false);
	vector<int> pr;
	for(int i = 2; i <= n; i++){
		if(!ch[i]){
			pr.push_back(i);
			for(int j = 1; i*j<=n; j++){
				ch[i*j]=true;
			}
		}
	}
	return pr;
}

//最大公約数(ユークリッドの互除法）
ll gcd (ll a, ll b){
	if(b>a){
		swap(a, b);
	}
	while(a%b!=0){
		ll t = a;
		a = b;
		b = t%b;
	}
	return b;
}

//最小公倍数（gcdを定義しておく）
ll lcm (ll a, ll b){
	ll g = gcd(a, b);
	ll x = (a/g)*b;
	return x;
}

//角XYZ(偏角Z→X)の角度（[0,2π)）
double angle(vector<double> X, vector<double> Y, vector<double>Z) {
	vector<double> x = { X[0] - Y[0],X[1] - Y[1] };
	vector<double> z = { Z[0] - Y[0],Z[1] - Y[1] };

	double pre, post;
	pre = atan2(x[1], x[0]);
	post = atan2(z[1], z[0]);
	if (post < 0) {
		post += pi*2;
	}
	if (pre < 0) {
		pre += pi*2;
	}
	if (pre < post) {
		pre += pi * 2;
	}
	return pre - post;
}

//mod mod下で逆元を算出する
//高速a^n計算(mod ver.)
ll mypower(ll a, ll n, ll Mod=mod) {
	if (n == 0) {
		return 1;
	}
	else if (n % 2 == 0) {
		ll x = mypower(a, n / 2,Mod);
		x *= x;
		x %= Mod;
		return x;
	}
	else {
		ll x = mypower(a, n - 1,Mod);
		x *= a;
		x %= Mod;
		return x;
	}
}
//フェルマーの小定理を利用
ll modinv(ll p, ll Mod=mod) {
	return mypower(p, Mod - 2,Mod) % Mod;
}

////素因数分解（osa_k法）（前計算O(N)、素数判定O(1)、素因数分解(O(logN)） //エラトステネスの篩の代わりとしても使える(N項のvectorを生成するため、巨大数に対しては√Nまでの素数リストを作って割る方が良い)
struct osa_k {
	//最大値までの各自然数に対し、その最小の素因数を格納するリスト
	vector<int> min_prime_list;
	int upper_limit;
	osa_k(int N) {
		//N:最大値。一つの自然数の素因数分解にしか興味が泣ければそれを入力
		vector<int> v(N + 1);
		upper_limit = N;
		rep(i, N + 1) {
			v[i] = i;
		}
		swap(min_prime_list, v);

		//k=2から見る
		for (int k = 2; k * k <= N; k++) {
			if (min_prime_list[k] == k) {
				//最小の素因数=自分ならば、素数
				//kが素数の時、t=k*kから始めてt=Nまでのkの倍数全てを確認する。未更新の自然数があれば、それの最小の素因数をkに更新する。
				//k*k未満のkの倍数に対しては、kが最小の素因数にはなり得ないので計算する必要が無い
				for (int t = k * k; t <= N; t += k) {
					if (min_prime_list[t] == t) {
						min_prime_list[t] = k;
					}
				}
			}
		}
	}

	//任意の自然数nが素数であればtrueを返す
	bool isPrime(int n) {
		if (n < 2) {
			return false;
		}
		else {
			return min_prime_list[n] == n;
		}
	}

	//任意の自然数nの素因数分解を行う。素因数はvectorで与えられる（ex:n=12 -> {2,2,3}）
	vector<int> devPrimes(int n) {
		vector<int> vec;
		int now = n;
		while (now > 1) {
			vec.push_back(min_prime_list[now]);
			now /= min_prime_list[now];
		}
		return vec;
	}
};


//最大流問題を解く構造体(Ford-Fulkerson法.O(FE))
struct maxflow {
	struct Edge {
		int to, rev;
		ll capacity, init_capacity;
		int off, on;
		Edge(int _to, int _rev, ll _capacity, int _off, int _on) :to(_to), rev(_rev), capacity(_capacity), init_capacity(_capacity), off(_off), on(_on) {};
	};
	int delay=0;
	
	vector<vector<Edge>> Graph;

	maxflow(int MAX_V, int d) {
		Graph.assign(MAX_V, {});
		delay=d;
	}

	void input(int from, int to, ll capacity, int off, int on) {
		int e_id = Graph[from].size();
		int r_id = Graph[to].size();
		Graph[from].push_back(Edge(to, r_id, capacity, off, on));
		Graph[to].push_back(Edge(from, e_id, 0, on+delay, off-delay));
	}

	Edge& rev_Edge(Edge& edge) {
		return Graph[edge.to][edge.rev];
	}

	vector<bool> visited;
	ll dfs(int now, int g, ll flow, int time) {
		visited[now] = true;
		if (now == g) {
			return flow;
		}
		else {
			ll f = 0;
			ll res_flow = flow;
			for (Edge& edge : Graph[now]) {
				if (!visited[edge.to] && edge.capacity > 0 && edge.off>=time && edge.on<=1e9) {
					ll f_delta = dfs(edge.to, g, min(res_flow, edge.capacity), edge.on+delay);	
					edge.capacity -= f_delta;
					rev_Edge(edge).capacity += f_delta;
					f += f_delta;
					res_flow -= f_delta;
					if (res_flow == 0) {
						break;
					}
				}
			}
			return f;
		}
	}

	void flowing(int s, int g, ll init_flow = INF) {
		bool cont = true;
		while (cont) {
			visited.assign(Graph.size(), false);
			ll flow = dfs(s, g, init_flow,0);
			init_flow -= flow;
			if (flow == 0) {
				cont = false;
			}
		}
	}

	ll get_flow(int g) {
		ll flow = 0;
		for (Edge& edge : Graph[g]) {
			Edge& rev_edge = rev_Edge(edge);
			ll tmp_flow = rev_edge.init_capacity - rev_edge.capacity;
			if (tmp_flow > 0) {
				flow += tmp_flow;
			}
		}
		return flow;
	}

	vector<tuple<int, int, ll>> flowing_edges() {
		vector<tuple<int, int, ll>> vec;
		rep(from, Graph.size()) {
			for (Edge& edge : Graph[from]) {
				ll flow = edge.init_capacity - edge.capacity;
				if (flow > 0) {
					vec.push_back({ from,edge.to,flow });
				}
			}
		}
		return vec;
	}
};

//Dinic法でのmax-flow。最大マッチングなど辺のキャパシティが小さい場合には高速
struct Dinic {
	struct Edge {
		int to, rev;
		ll capacity, init_capacity;
		ld cost;
		Edge(int _to, int _rev, ll _capacity,ld _cost) :to(_to), rev(_rev), capacity(_capacity),init_capacity(_capacity),cost(_cost) {};
	};

	vector<vector<Edge>> Graph;

	Edge& rev_Edge(Edge& edge) {
		return Graph[edge.to][edge.rev];
	}
	vector<int> level,itr;

	Dinic(int MAX_V) {
		Graph.assign(MAX_V, {});
	}

	void input(int _from, int _to, ll _capacity,ld _cost) {
		int e_id = Graph[_from].size(), r_id = Graph[_to].size();
		Graph[_from].push_back(Edge(_to, r_id, _capacity,_cost));
		Graph[_to].push_back(Edge(_from, e_id, 0LL,_cost));
	}

	void bfs(int s, int g, ld val) {
		level.assign(Graph.size(), -1);
		level[s] = 0;
		queue<int> q;
		q.push(s);
		while (!q.empty()) {
			int now = q.front();
			q.pop();
			if (now == g) {
				continue;
			}
			for (Edge &e : Graph[now]) {
				if (level[e.to] == -1 && e.capacity > 0 && e.cost<=val) {
					level[e.to] = level[now] + 1;
					q.push(e.to);
				}
			}
		}
	}

	ll dfs(int now, int g, ll flow, ld val) {
		if (now == g) {
			return flow;
		}
		else if (level[now] >= level[g]) {
			return 0; //gよりも深い場所に行こうとしたら終わり。flow=0を返す
		}
		else {
			ll res_flow = flow;
			ll f = 0;
			for (int &i = itr[now]; i < Graph[now].size(); i++) {
				Edge& edge = Graph[now][i];
				if (level[edge.to] == level[now] + 1 && edge.capacity > 0 && edge.cost<=val) {
					ll f_delta = dfs(edge.to, g, min(res_flow, edge.capacity), val);
					edge.capacity -= f_delta;
					rev_Edge(edge).capacity += f_delta;
					res_flow -= f_delta;
					f += f_delta;
					if (res_flow == 0) {
						break;
					}
				}
			}
			return f; //行先が無い場合はflow=0を返す
		}
	}

	void flowing(int s, int g, ll init_flow = INF, ld val=0) {
		bool cont1 = true;
		while (cont1) {
			bfs(s, g,val);
			if (level[g] == -1) {
				cont1 = false;
			}
			else {
				bool cont2 = true;
				while (cont2) {
					itr.assign(Graph.size(), 0);
					ll flow = dfs(s, g, init_flow,val);
					init_flow -= flow;
					if (flow == 0) {
						cont2 = false;
					}
				}
			}
			if(init_flow==0){
				cont1=false;
			}
		}
	}

	ll get_flow(int g) {
		ll flow = 0;
		for (Edge& edge : Graph[g]) {
			flow += max(0LL, rev_Edge(edge).init_capacity - rev_Edge(edge).capacity);
		}
		return flow;
	}

	vector<tuple<int, int, ll>> flowing_edges(){
		vector<tuple<int,int,ll>> vec;
		for (int from = 0; from < Graph.size(); from++) {
			for (Edge& edge : Graph[from]) {
				if (edge.init_capacity - edge.capacity > 0) {
					vec.push_back({ from,edge.to,edge.init_capacity - edge.capacity });
				}
			}
		}
		return vec;
	}

	void reset() {
		for (int from = 0; from < Graph.size(); from++) {
			for (Edge& edge : Graph[from]) {
				edge.capacity = edge.init_capacity;
			}
		}
	}
};

//小さい方/大きい方からk番目の値を取り出せる平衡二分木
template <typename T>
struct ordered_set{
  struct node{
    T val; //載せたい値。不等式で順序が定義されるものにする
    int prio; //優先度（ランダムに付与される。平衡化するために必要）
    int id; //この頂点のindex
    int par; //親のindex
    int cl; //子の内小さい方のindex
    int cr; //子の内大きい方のindex
    int size; //この頂点を根とする部分木の大きさ
    bool survive; //eraseされたらfalseになる
    node(int _val=0,int _id=-1, int _par=-1, int _cl=-1, int _cr=-1){
      val=_val;
      id=_id;
      prio=rand();
      par=_par;
      cl=_cl;
      cr=_cr;
      size=1;
      survive=true;
    }
  };

  vector<node> tree;
  int root;

  ordered_set(){
    srand(int(time(NULL)));
    tree={};
    root=-1;
  }

	int size(){
		return root==-1?0:tree[root].size;
	}

  int calc_size(node &n){
    int ret=1;
    if(n.cl!=-1){
      ret+=tree[n.cl].size;
    }
    if(n.cr!=-1){
      ret+=tree[n.cr].size;
    }
    n.size=ret;
    return ret;
  }

  int find(T val){
    int now=root;
    while(now!=-1){
      if(tree[now].val==val){
        break;
      }
      if(tree[now].val>=val){
        now=tree[now].cl;
      }
      else{
        now=tree[now].cr;
      }
    }
    return now;
  }

  bool count(T val){
		int id=find(val);
		if(id==-1 || !tree[id].survive){
			return false;
		}
		else{
			return true;
		}
  }

	bool empty(){
		return size()==0;
	}

  void rotate(node &c, node &p){
    if(p.par!=-1){
      if(tree[p.par].cl==p.id){
        tree[p.par].cl=c.id;
      }
      else{
        tree[p.par].cr=c.id;
      }
    }
    if(c.val<=p.val){
      if(c.cr!=-1){
        tree[c.cr].par=p.id;
      }
      p.cl=c.cr;
      c.cr=p.id;
      c.par=p.par;
      p.par=c.id;
    }
    else{
      if(c.cl!=-1){
        tree[c.cl].par=p.id;
      }
      p.cr=c.cl;
      c.cl=p.id;
      c.par=p.par;
      p.par=c.id;
    }
		calc_size(p);
  }

  void add_child(node &c, node &p){
    c.par=p.id;
    if(c.val<=p.val){
      p.cl=c.id;
    }
    else{
      p.cr=c.id;
    }
    p.size++;
  }

  bool insert(T val){
    int id=find(val);

		if(id==-1){
			tree.push_back(node(val, tree.size()));
			node &neo=tree[tree.size()-1];
			if(root==-1){
				root=neo.id;
			}
			else{
				int p=root;
				while(true){
					tree[p].size++;
					int c;
					if(tree[p].val>=val){
						c=tree[p].cl;
					}
					else{
						c=tree[p].cr;
					}
					if(c!=-1){
						p=c;
					}
					else{
						break;
					}
				}
				add_child(neo, tree[p]);
				while(neo.par!=-1){
					if(tree[neo.par].prio>neo.prio){
						break;
					}
					else{
						rotate(neo, tree[neo.par]);
					}
				}
				calc_size(neo);

				if(neo.par==-1){
					root=neo.id;
				}
			}
			return true;
		}

		else if(tree[id].survive){
			return false;
		}

		else {
			tree[id].survive=true;
			int now=id;
			while(now!=-1){
				tree[now].size++;
				now=tree[now].par;
			}
			return true;
		}
  }

  bool erase(T val){
    int id=find(val);
    if(id==-1){
      return false;
    }
		else if(!tree[id].survive){
			return false;
		}
    else{
      tree[id].survive=false;
      int now=id;
      while(now!=-1){
        tree[now].size--;
        now=tree[now].par;
      }

      return true;
    }
  }

  T find_kth_min(int k){
    assert(k<=size());
    int now=root;
    while(true){
			if(tree[now].survive){
				int tmp=1;
				if(tree[now].cl!=-1){
					tmp+=tree[tree[now].cl].size;
				}
				if(tmp==k){
					break;
				}
				else if(tmp<k){
					k-=tmp;
					now=tree[now].cr;
				}
				else{
					now=tree[now].cl;
				}
			}
			else{
				int tmp=0;
				if(tree[now].cl==-1){
					now=tree[now].cr;
				}
				else if(tree[now].cr==-1){
					now=tree[now].cl;
				}
				else{
					if(tree[tree[now].cl].size>=k){
						now=tree[now].cl;
					}
					else{
						k-=tree[tree[now].cl].size;
						now=tree[now].cr;
					}
				}
			}
    }
    return tree[now].val;
  }

  T find_kth_max(int k){
    assert(k<=size());
    int now=root;
    while(true){
			if(tree[now].survive){
				int tmp=1;
				if(tree[now].cr!=-1){
					tmp+=tree[tree[now].cr].size;
				}
				if(tmp==k){
					break;
				}
				else if(tmp<k){
					k-=tmp;
					now=tree[now].cl;
				}
				else{
					now=tree[now].cr;
				}
			}
			else{
				int tmp=0;
				if(tree[now].cr==-1){
					now=tree[now].cl;
				}
				else if(tree[now].cl==-1){
					now=tree[now].cr;
				}
				else{
					if(tree[tree[now].cr].size>=k){
						now=tree[now].cr;
					}
					else{
						k-=tree[tree[now].cr].size;
						now=tree[now].cl;
					}
				}
			}
    }
    return tree[now].val;
  }

	int lower_count(T val){
		//valより小さい値の個数を返す
		int ret=0;
		int now=root;
		while(now!=-1){
			if(tree[now].val<val){
				if(tree[now].cl!=-1){
					ret+=tree[tree[now].cl].size;
				}
				now=tree[now].cr;
			}
			else{
				now=tree[now].cl;
			}
		}
		return ret;
	}

	int lower_or_equal_count(T val){
		//val以下の値の個数を返す
		int ret=0;
		int now=root;
		while(now!=-1){
			if(tree[now].val<=val){
				if(tree[now].cl!=-1){
					ret+=tree[tree[now].cl].size;
				}
				if(tree[now].survive){
					ret++;
				}
				now=tree[now].cr;
			}
			else{
				now=tree[now].cl;
			}
		}
		return ret;
	}

	int upper_count(T val){
		//valより大きい値の個数を返す
		return tree[root].size - lower_or_equal_count(val);
	}

	int upper_or_equal_count(T val){
		//val以上の値の個数を返す
		return tree[root].size - lower_count(val);
	}
};


int main(){
	int N;
	cin>>N;
	vector<vector<int>> path(N);
	map<int,map<int,ll>> cost;
	rep(i,N-1){
		int u,v;
		ll c;
		cin>>u>>v>>c;
		u--;
		v--;
		path[u].push_back(v);
		path[v].push_back(u);
		cost[u][v]=c;
		cost[v][u]=c;
	}


	ll ans=0;
	vector<vector<int>> child(N);
	vector<bool> check(N,false);
	function<void(int)> make_tree=[&](int now){
		for(int x:path[now]){
			if(!check[x]){
				check[x]=true;
				child[now].push_back(x);
				make_tree(x);
			}
		}
	};
	check[0]=true;

	vector<vector<ll>> score(N,{0});

	function<void(int)> solve=[&](int now){
		for(int c:child[now]){
			solve(c);
			score[now].push_back(score[c][0]+cost[now][c]);
		}
		if(score[now].size()>=2){
			rsort(score[now]);
			ans=max(ans, score[now][0]+score[now][1]);
		}
	};

	make_tree(0);
	solve(0);

	cout<<ans<<endl;
}