#include <iostream>
#include <fstream>
#include <algorithm>
#include <vector>
#include <queue>
#include <memory.h>

#define newn G[nod][i]

using namespace std;

ifstream fin("darb.in");
ofstream fout("darb.out");

const int Nmax = 1e5 + 100;

int N, DIST[Nmax], last = 1;
vector <int> G[Nmax];
vector <bool> viz(Nmax);
queue <int> Q;

void DFS(int s)
{
    viz.assign(N + 1, 0);
    memset(DIST, 0, sizeof DIST);
    Q.push(s); DIST[s] = 1; viz[s] = 1;
    while(!Q.empty())
    {
        int nod = Q.front(); Q.pop();
        last = nod;
        for(unsigned i = 0; i < G[nod].size(); i++)
            if(!viz[newn])
            {
                viz[newn] = 1;
                DIST[newn] = DIST[nod] + 1;
                Q.push(newn);
            }
    }
}

int main()
{
    fin >> N;
    for(int i = 1; i < N; i++)
    {
        int x, y;
        fin >> x >> y;
        G[x].push_back(y);
        G[y].push_back(x);
    }

    DFS(last);
    DFS(last);
    fout << DIST[last];
    return 0;
}