#include <bits/stdc++.h>
using namespace std;
ifstream fin("darb.in");
ofstream fout("darb.out");

long long n, maxDist, farNode;
vector<vector<int>> adj;

void dfs_diam(int nod, int par, int dist)
{
    if(dist > maxDist)
    {
        maxDist = dist;
        farNode = nod;
    }
    for(int neigh : adj[nod])
    {
        if(par == neigh) continue;
        dfs_diam(neigh, nod, dist + 1);
    }
}

int tree_diam()
{
    dfs_diam(1, 0, 1);
    int X = farNode;
    dfs_diam(X, 0, 1);
    return maxDist;
}

void solve()
{
    int i;
    fin >> n;
    adj.resize(n+1);
    for(i = 1; i < n; i++)
    {
        int x, y;
        fin >> x >> y;
        adj[x].push_back(y);
        adj[y].push_back(x);
    }
    fout << tree_diam();
    return;
}

int main()
{

    long long t;
    solve();

    return 0;
}