#include <iostream>
#include <fstream>
#include <vector>
#include <cstring>
#include <queue>

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

#define MAX 100001

int N,x,y,i, diametru, last;
vector <int> A[MAX];
int d[MAX];
queue<int> coada;

void citire()
{
    f >> N;
    for (i = 1; i <= N; i++)
    {
        f >> x >> y;
        A[x].push_back(y);
        A[y].push_back(x);
    }
}

void BFS(int nod)
{
    diametru = 1;
    memset(d, 0, sizeof(d));
    d[nod] = 1;
    coada.push(nod);

    while (!coada.empty())
    {
        nod = coada.front();
        coada.pop();

        for (auto j: A[nod])
        {
            if (!d[j])
            {
                d[j] = d[nod] + 1;
                diametru = max(diametru, d[j]);
                coada.push(j);
                last = j;
            }
        }
    }
}

int main()
{
    citire();

    BFS(1);
    BFS(last);

    cout<<diametru;

    return 0;
}