#include <bits/stdc++.h>

using namespace std;

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

int n, gradMax, root, MAX1, MAX2;
vector <int> Muchii[100001];
queue <int> coada;
int vizitat[100001];

void citire()
{
    int x, y;
    in >> n;
    for (int i = 1; i < n; ++i)
    {
        in >> x >> y;
        Muchii[x].push_back(y);
        Muchii[y].push_back(x);
        if (Muchii[x].size() > gradMax)
        {
            gradMax = Muchii[x].size();
            root = x;
        }
        if (Muchii[y].size() > gradMax)
        {
            gradMax = Muchii[y].size();
            root = y;
        }
    }
}

void BFS(int nodStart)
{
    int nod, vecin;
    coada.push(nodStart);
    while (!coada.empty())
    {
        nod = coada.front();
        if (vizitat[nod] > MAX1)
        {
            MAX2 = MAX1;
            MAX1 = vizitat[nod];
        }
        else if (vizitat[nod] > MAX2 && vizitat[nod] <= MAX1)
            MAX2 = vizitat[nod];
        coada.pop();
        for (int i = 0; i < Muchii[nod].size(); ++i)
        {
            vecin = Muchii[nod][i];
            if (!vizitat[vecin] && vecin != root)
            {
                vizitat[vecin] = vizitat[nod] + 1;
                coada.push(vecin);
            }
        }
    }
}

int main()
{
    citire();
    for (int i = 0; i < Muchii[root].size(); ++i)
    {
        int vecin = Muchii[root][i];
        vizitat[vecin] = 1;
        BFS(vecin);
    }
    out << MAX1 + MAX2 + 1;
    return 0;
}