#include <iostream>
#include <fstream>
#include <queue>
#include <string.h>
#define N 1000001
using namespace std;

ifstream f("darb.in");
ofstream g("darb.out");

vector <int> L[N];
int n,m,viz[N],cnt[N],diam,ulta,p,last;
queue <int> c;
void Read()
{
    short x,y;
    f >> n;
    for(short i = 1; i < n; i++)
    {
        f >> x >> y;
        L[x].push_back(y);
        L[y].push_back(x);
    }
    f.close();
}
void BFS(int p)
{
    memset(viz,0,N);
    memset(cnt,0,N);
    c.push(p);
    cnt[p] = 1;
    viz[p] = 1;
    int i , el;
    while(!c.empty())
    {
        el = c.front();
        for(i = 0; i < L[el].size();i++)
        {
            if(!viz[L[el][i]])
            {
                c.push(L[el][i]);
                cnt[L[el][i]] = cnt[el] + 1;
                viz[L[el][i]] = 1;
                diam = cnt[L[el][i]];
                last = L[el][i];
            }
        }
        c.pop();
    }
}
int main()
{
    Read();
    BFS(1);
    BFS(last);
    g << diam;
    return 0;
}