// Slower C++ solution:
#include <iostream>

#include <iomanip>

#include <cstdio>

#include <string>

#include <cstring>

#include <deque>

#include <list>

#include <queue>

#include <stack>

#include <vector>

#include <utility>

#include <algorithm>

#include <map>

#include <set>

#include <complex>

#include <cmath>

#include <limits>

#include <cfloat>

#include <climits>

#include <ctime>

#include <cassert>

using namespace std;



#define rep(i,a,n) for(int (i)=(a); (i)<(n); (i)++)

#define repq(i,a,n) for(int (i)=(a); (i)<=(n); (i)++)

#define repr(i,a,n) for(int (i)=(a); (i)>=(n); (i)--)

#define all(v) begin(v), end(v)

#define pb(a) push_back(a)

#define fr first

#define sc second

#define INF 2000000000

#define int long long int



#define X real()

#define Y imag()

#define EPS (1e-10)

#define EQ(a,b) (abs((a) - (b)) < EPS)

#define EQV(a,b) ( EQ((a).X, (b).X) && EQ((a).Y, (b).Y) )

#define LE(n, m) ((n) < (m) + EPS)

#define LEQ(n, m) ((n) <= (m) + EPS)

#define GE(n, m) ((n) + EPS > (m))

#define GEQ(n, m) ((n) + EPS >= (m))



typedef vector<int> VI;

typedef vector<VI> MAT;

typedef pair<int, int> pii;

typedef long long ll;



typedef complex<double> P;

typedef pair<P, P> L;

typedef pair<P, double> C;



int dx[]={1, -1, 0, 0};

int dy[]={0, 0, 1, -1};

int const MOD = 1000000007;

ll mod_pow(ll x, ll n) {return (!n)?1:(mod_pow((x*x)%MOD,n/2)*((n&1)?x:1))%MOD;}

int madd(int a, int b) {return (a + b) % MOD;}

int msub(int a, int b) {return (a - b + MOD) % MOD;}

int mmul(int a, int b) {return (a * b) % MOD;}

int minv(int a) {return mod_pow(a, MOD-2);}

int mdiv(int a, int b) {return mmul(a, minv(b));}



namespace std {

    bool operator<(const P& a, const P& b) {

        return a.X != b.X ? a.X < b.X : a.Y < b.Y;

    }

}



struct Edge {

    int to, cost;

};



vector<Edge> G[100010];

int dist[100010];



void dfs(int idx, int par) {

    for(auto &e : G[idx]) {

        if(e.to == par) continue;

        dfs(e.to, idx);

        dist[idx] = max(dist[idx], dist[e.to] + e.cost);

    }

}



int dfs2(int idx, int d_par, int par) {

    vector<pii> rec;

    rec.push_back(pii(0, -1));

    for(auto &e : G[idx]) {

        if(e.to == par) rec.push_back(pii(d_par + e.cost, e.to));

        else rec.push_back(pii(dist[e.to] + e.cost, e.to));

    }

    sort(rec.rbegin(), rec.rend());

    int ret = rec[0].first + rec[1].first;

    for(auto &e : G[idx]) {

        if(e.to == par) continue;

        ret = max(ret, dfs2(e.to, rec[ rec[0].second == e.to ].first, idx));

    }

    return ret;

}



signed main() {

    int n; cin >> n;

    rep(i,0,n-1) {

        int s, t, w; cin >> s >> t >> w;

        G[s].push_back(Edge{t, w});

        G[t].push_back(Edge{s, w});

    }

    dfs(0, -1);

    cout << dfs2(0, 0, -1) << endl;

}

// Faster C++ solution for the same problem (measured speedup: 3.8072020463696465x):
#include <cstdio>

#include <vector>

#include <algorithm>

#include <utility>

using namespace std;



struct Edge {

    int to, cost;

};

using Graph = vector< vector<Edge> >;



int dist[100010];



// dist[i] := 頂点 i から最も遠い葉との距離

void dfs(Graph &G, int cur, int par=-1) {

    for(auto e : G[cur]) {

        if(e.to == par) continue;

        dfs(G, e.to, cur);

        dist[cur] = max(dist[cur], dist[e.to] + e.cost);

    }

}



int solve(Graph &G, int root, int d_par, int par=-1) {

    vector< pair<int, int> > children;

    children.push_back(make_pair(0, -1));



    for(auto e : G[root]) {

        if(e.to == par) children.push_back(make_pair(d_par + e.cost, e.to));

        else children.push_back(make_pair(dist[e.to] + e.cost, e.to));

    }

    sort(children.begin(), children.end(), greater< pair<int, int> >());



    int max_cost = children[0].first + children[1].first;

    for(auto e : G[root]) {

        if(e.to == par) continue;

        int nxt_d_par = children[children[0].second == e.to].first;

        max_cost = max(max_cost, solve(G, e.to, nxt_d_par, root));

    }

    return max_cost;

}



int main() {

    int N; scanf("%d", &N);



    Graph G(N);

    for(int i=0; i<N-1; i++) {

        int s, t, w; scanf("%d%d%d", &s, &t, &w);

        G[s].push_back(Edge{t, w});

        G[t].push_back(Edge{s, w});

    }

    dfs(G, 0);

    printf("%d\n", solve(G, 0, 0));

}