#include <iostream>
#include <fstream>
#include <vector>

using namespace std;

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

vector <int> g[100005];
int l[100005];

void dfs(int nod)
{
    for (int i = 0; i < g[nod].size(); i++)
        if (l[g[nod][i]] == 0)
        {
            l[g[nod][i]] = l[nod] + 1;
            dfs(g[nod][i]);
        }
}

int main()
{
    int n;
    fin >> n;
    for (int i = 1; i < n; i++)
    {
        int x, y;
        fin >> x >> y;
        g[x].push_back(y);
        g[y].push_back(x);
    }
    l[1] = 1;
    dfs(1);
    int mare = 0, ind;
    for (int i = 1; i <= n; i++)
    {
        if (l[i] > mare)
        {
            mare = l[i];
            ind = i;
        }
        l[i] = 0;
    }
    l[ind] = 1;
    dfs(ind);
    for (int i = 1; i <= n; i++)
        if (l[i] > mare)
            mare = l[i];
    fout << mare << '\n';
    return 0;
}