#include <iostream>
#include <fstream>
#include <vector>
#include <queue>
using namespace std;

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

const int NMAX = 100000;

vector<int> A[NMAX + 1];
int dist[NMAX + 1];
int n;

int bfs(int start)
{
    queue<int> q;
    for(int i = 1; i <= n; i++)
        dist[i] = -1;
    dist[start] = 0;
    q.push(start);
    int last = start;
    while(!q.empty())
    {
        int nod = q.front();
        q.pop();
        last = nod;
        for(int i = 0; i < A[nod].size(); i++)
        {
            int vecin = A[nod][i];
            if(dist[vecin] == -1)
            {
                dist[vecin] = dist[nod] + 1;
                q.push(vecin);
            }
        }
    }
    return last;
}

int main()
{
    int x, y;
    f >> n;
    for(int i = 1; i < n; i++)
    {
        f >> x >> y;
        A[x].push_back(y);
        A[y].push_back(x);
    }
    int A1 = bfs(1);
    int A2 = bfs(A1);
    g << dist[A2] + 1;
    f.close();
    g.close();
    return 0;
}