#include<iostream>

#include<cstdio>

#include<cstdlib>

#include<algorithm>

#include<cstring>

#include<cmath>

#define ll long long

using namespace std;

inline int read()

{

    int x=,f=;

    char ch=getchar();

    while(!isdigit(ch)){if(ch=='-')f=-f;ch=getchar();}

    while(isdigit(ch)){x=*x+ch-'';ch=getchar();}

    return x*f;

}

int n,first[],to[],next[],val[],cnt;

inline void add(int u,int v,int w)

{

    to[++cnt]=v;

    next[cnt]=first[u];

    first[u]=cnt;

    val[cnt]=w;

}

int dp[][],depth1[],depth2[];

int dfs1(int x,int fa)

{

    for(int i=first[x];i;i=next[i])

    {

        int v=to[i];

        if(v==fa)continue;

        dp[x][]=max(dfs(v)+val[i],dp[x][]);

    }

    return dp[x][];

}

int vis[];

int dfs2(int x,int fav)

{

    int max1=,max2=;

    int flag1,flag2;

    if(vis[x])continue;

    for(int i=first[x];i;i=next[i])

    {

        int v=to[i];

        if(vis[v])continue;

        int tmp=dp[v][]+val[i];

        if(tmp>max1)

        {

            max2=max1;

            max1=tmp;

            flag2=flag1;

            flag1=v;

        }

        if(tmp==max1 || tmp>max2)

        {

            max2=max1;

            max1=tmp;

            flag2=v;

        }

    }

    if(x!=)

    {

        int tmp=dp[x][];

        int v=-;

        if(tmp>max1)

        {

            max2=max1;

            max1=tmp;

            flag2=flag1;

            flag1=v;

        }

        if(tmp==max1 || tmp>max2)

        {

            max2=max1;

            max1=tmp;

            flag2=v;

        }

    }

    for(int i=first[x];i;i=next[i])

    {

        int v=to[i];

        if(v==flag1)

            dp[x][]=max2+val[i];

        else dp[x][]=max1+val[i];

        dfs2(v,val[i]);

    }

}

int main()

{

    n=read();

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

    {

        int u,v,w;

        u=read();v=read();w=read();

        add(u,v,w);add(v,u,w);

    }

    dfs1(,-);

}