#include<cstdio>

#include<algorithm>

#include<cstring>

using namespace std;

const int maxn=;

struct edge{int from,v,w;}e[maxn*];

int tot,X,n,head,tail,q[maxn],d[maxn],first[maxn];

bool v[maxn];

void insert(int u,int v,int w)

{tot++;e[tot].v=v;e[tot].w=w;e[tot].from=first[u];first[u]=tot;}

void bfs(int s)

{

    X=;

    memset(d,,sizeof(d));

    memset(v,,sizeof(v));//数组，值，范围

    head=;tail=;q[]=s;v[s]=;

    while(head<=tail)

     {

         int u=q[head++];

         if(d[u]>d[X])X=u;

         for(int i=first[u];i;i=e[i].from)

          if(!v[e[i].v])

           {

               v[e[i].v]=;

               d[e[i].v]=d[u]+e[i].w;

               q[++tail]=e[i].v;

           }

     }

}

int main()

{

    scanf("%d",&n);

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

     {

         int u,v,w;

         scanf("%d%d%d",&u,&v,&w);

         insert(u,v,w);

         insert(v,u,w);

     }

    bfs();

    bfs(X);

    printf("%d",d[X]);

    return ;

}