#include <stdio.h>

#include <algorithm>

#include <iostream>

using namespace std;

struct node

{

    int x, y, id;

}E[];

bool cmp(node A, node B)

{

    if(A.x == B.x) return A.y < B.y;

    else return A.x < B.x;

}

int n, zd, rt;

int to[];

int dis[];

int nex[];

int head[];

void dfs(int x, int fa)

{

    int c = head[x];

    for(int i = c; i; i = nex[i])

    {

        int v = to[i];

        if(v == fa) continue;

        dis[v] = dis[x] + ;

        if(dis[v] > zd) rt = v, zd = dis[v];

        dfs(v, x);

    }

}

int main()

{

    zd = rt = ;

    scanf("%d", &n);

    int cnt = ;

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

    {

        int a, b, c;

        scanf("%d%d%d", &a, &b, &c);

        if(a < b) swap(a, b);

        if(b < c) swap(b, c);

        if(a < b) swap(a, b);

        E[++cnt].x = a; E[cnt].y = b; E[cnt].id = i;

        E[++cnt].x = b; E[cnt].y = c; E[cnt].id = i;

        E[++cnt].x = a; E[cnt].y = c; E[cnt].id = i;

    }

    sort(E + , E +  + cnt, cmp);

    int cn = ;

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

    {

        if(E[i].x == E[i - ].x && E[i].y == E[i - ].y)

        {

            int u = E[i].id; int v = E[i - ].id;

            to[++cn] = u; nex[cn] = head[v]; head[v] = cn;

            to[++cn] = v; nex[cn] = head[u]; head[u] = cn;

        }

    }

    dfs(, -);

    zd = ; int l = rt;

    dis[rt] = ;

    dfs(rt, -);

    printf("%d\n", zd);

    return ;

}