#include <bits/stdc++.h>

using namespace std;

ifstream fin("darb.in");
ofstream fout("darb.out");
int n, sol;
vector <int> v[100005];
int dp[100005];
inline void Citire()
{
    fin >> n;
    for(int i = 1; i <= n; i ++)
    {
        int x, y;
        fin >> x >> y;
        v[x].push_back(y);
        v[y].push_back(x);
    }
}
inline void dfs(int nod, int tata)
{
    int maxim1 = 0, maxim2 = 0;
    for(auto it: v[nod])
    {
        if(it == tata)
            continue;
        dfs(it, nod);
        if(dp[it] >= maxim1)
        {
            maxim2 = maxim1;
            maxim1 = dp[it];
        }
        else if(dp[it] > maxim2)
            maxim2 = dp[it];
    }
    dp[nod] = maxim1 + 1;
    sol = max(maxim1 + maxim2 + 1, sol);
}
int main()
{
    Citire();
    dfs(1, 0);
    fout << sol;
    return 0;
}