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

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

using VI = vector<int>;
int N;
vector<vector<int>> G;
VI d, v;
int l;

void Read();
void BFS( int nod );

int main()
{
    Read();
    BFS(1);
    BFS(l);

    fout << d[l] << '\n';

    fin.close();
    fout.close();
    return 0;
}

void Read()
{
    int x, y;
    fin >> N;
    G = vector<VI>(N + 1);
    for ( int i = 1; i < N; ++i )
    {
        fin >> x >> y;

        G[x].push_back(y);
        G[y].push_back(x);
    }
}

void BFS( int nod )
{
    d = v = VI(N + 1, 0);
    queue<int> Q;

    Q.push(nod);
    d[nod] = 1;
    while ( !Q.empty() )
    {
        int x = Q.front();
        Q.pop();

        for ( const int& y : G[x] )
            if ( !v[y] )
            {
                v[y] = true;
                d[y] = d[x] + 1;
                l = y;

                Q.push(y);
            }
    }
}