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/* -----------------------
Autor: Tomasz Boguslawski
-------------------------- */
#include<cstdio>
#include<cstdlib>
#include<iostream>
#include<fstream>
#include<iomanip>
#include<string>
#include<sstream>
#include<cstring>
#include<map>
#include<vector>
#include<set>
#include<queue>
#include<stack>
#include<algorithm>
#include <fstream>
#include<math.h>

#define FOR(x, b, e) for(long x = b; x <= (e); x++)
#define FORD(x, b, e) for(long x = b; x >= (e); x--)
#define VAR(v, n) __typeof(n) v = (n)
#define ALL(c) (c).begin(), (c).end()
#define FOREACH(i, c) for(VAR(i, (c).begin()); i != (c).end(); ++i)
#define DEBUG if (debug)
#define MIN(a,b) ((a>b)?b:a)
#define MAX(a,b) ((a>b)?a:b)
#define LL long long

using namespace std;

LL n;
const LL h0=100000000;
const LL inf=-h0*h0;

class Node
{
public:
    LL num;
    LL parent;
    LL pass;
    LL w[4];
    vector<LL> nei;
    vector<LL> wei;
    Node() {};
    void addEdge(LL t, LL z) { nei.push_back(t); wei.push_back(z); };
};

Node nodes[210000];

void read_data()
{
	cin >> n;
    FOR(i,1,n) nodes[i].num=i;
    LL u,v,z;
    FOR(k,1,n-1)
    {
        cin >> u; cin >> v; cin >> z;
        nodes[u].addEdge(v,z);
        nodes[v].addEdge(u,z);
    }
}

LL maxDegreeNode()
{
    LL maxD=0; LL maxN=1;
    FOR(i,1,n)
    {
        LL deg=nodes[i].nei.size();
        if (deg>maxD) { maxD=deg; maxN=i; }
    }
    return maxN;
}

void makeTreeFrom(LL root)
{
    FOR(i,1,n) nodes[i].parent=0;
    queue<LL> toDo;
    FOREACH(nb,nodes[root].nei)
    {
        nodes[*nb].parent=root;
        toDo.push(*nb);
    }
    LL cur;
    while (!toDo.empty())
    {
        cur=toDo.front(); toDo.pop();
        FOREACH(nb,nodes[cur].nei) if ((*nb)!=nodes[cur].parent)
        {
            nodes[*nb].parent=cur;
            toDo.push(*nb);
        }
    }
}

void showTree(LL node, LL level)
{
    FOR(i,1,level) cout << "  ";
    cout << node << "\n";
    FOREACH(nb,nodes[node].nei) if (*nb != nodes[node].parent) showTree(*nb, level+1);
}

bool isLeaf(LL node, LL root)
{
    if (node==root) return nodes[node].nei.size()==0;
    else return nodes[node].nei.size()==1;
}

LL suma(LL v1, LL v2)
{
    if ((v1==inf)||(v2==inf)) return inf;
    return v1+v2;
}

void calculate_for(LL node, LL child, LL weight)
{
    //cout << "Calculating for node " << node << " and child " << child << " edgeWeight=" << weight << "\n";
    LL v[4];
    v[0]=max(nodes[child].w[0], suma(nodes[child].w[1],weight));
    v[1]=suma(weight, nodes[child].w[2]);
    v[2]=suma(weight, nodes[child].w[3]);
    v[3]=suma(weight, nodes[child].w[0]);
    if (nodes[node].w[0]==inf)
    {
        // this is first child
        FOR(j,0,3) nodes[node].w[j]=v[j];
        //cout << "Node " << node << " first child " << child << ": ";
        //FOR(j,0,3) cout << nodes[node].w[j] << " "; cout << "\n";
    }
    else
    {
        // next child
        //cout << "Node " << node << " next child " << child << "\n";
        //cout << " child values: "; FOR(j,0,3) cout << v[j] << " "; cout << "\n";
        LL p1=suma(nodes[node].w[0],v[0]);
        LL p2=suma(nodes[node].w[1],v[3]);
        LL p3=suma(nodes[node].w[2],v[2]);
        LL p4=suma(nodes[node].w[3],v[1]);
        LL m0=p1; if (p2>m0) m0=p2; if (p3>m0) m0=p3; if (p4>m0) m0=p4;

        p1=suma(nodes[node].w[1],v[0]);
        p2=suma(nodes[node].w[0],v[1]);
        LL m1=p1; if (p2>m1) m1=p2;

        p1=suma(nodes[node].w[2],v[0]);
        p2=suma(nodes[node].w[0],v[2]);
        LL m2=p1; if (p2>m2) m2=p2;

        p1=suma(nodes[node].w[3],v[0]);
        p2=suma(nodes[node].w[0],v[3]);
        //cout << "   p1=" << p1 << " p2=" << p2 << "\n";
        LL m3=p1; if (p2>m3) m3=p2;

        nodes[node].w[0]=m0;
        nodes[node].w[1]=m1;
        nodes[node].w[2]=m2;
        nodes[node].w[3]=m3;

        //cout << " calculated values: ";
        //FOR(j,0,3) cout << nodes[node].w[j] << " "; cout << "\n";

    }
}

void calculate(LL node, LL root)
{
    if (isLeaf(node, root))
    {
        nodes[node].w[0]=0;
        nodes[node].w[1]=inf;
        nodes[node].w[2]=inf;
        nodes[node].w[3]=inf;
    }
    else
    {
        FOR(i,0,nodes[node].nei.size()-1)
           if (nodes[node].nei[i]!=nodes[node].parent) calculate_for(node, nodes[node].nei[i], nodes[node].wei[i]);
    }
}

void go(LL root)
{
    FOR(i,1,n) { nodes[i].pass=0; FOR(j,0,3) nodes[i].w[j]=inf; };
    stack<LL> toDo;
    toDo.push(root);
    LL cur;
    while (!toDo.empty())
    {
        cur=toDo.top();
        if (nodes[cur].pass==0)
        {
            // first time
            nodes[cur].pass=1;
            FOREACH(nb,nodes[cur].nei) if (*nb!=nodes[cur].parent) toDo.push(*nb);
        }
        else
        {
            // second time
            toDo.pop();
            calculate(cur, root);
        }
    }
}

/// MAIN
int main(int argc, char* argv[])
{
    // magic formula, which makes streams work faster:
	ios_base::sync_with_stdio(0);
    read_data();
    LL root = maxDegreeNode();
    makeTreeFrom(root);
    //showTree(root,0);
    go(root);

    cout << nodes[root].w[0];

    return 0;
};