#include <bits/stdc++.h>

using namespace std;

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

int n, m, d[100001], viz[100001];
vector<int> h[100001];

void Citire()
{
    int y, x;
    fin >> n;
    while(fin >> x >> y)
    {
        h[x].push_back(y);
        h[y].push_back(x);
    }
}
void DFS(int k)
{
    viz[k] = 1;
    for (auto i : h[k])
        if (viz[i] == 0)
        {
            d[i] = d[k] + 1;
            DFS(i);
        }
}

int main()
{
    int i, MAX, M;
    Citire();
    DFS(1);
     MAX = d[1];
     M = 1;
    for (i = 2; i <= n; i++)
        if (d[i] > MAX)
           {
               MAX = d[i];
               M = i;
           }
    for (i = 1; i <= n; i++)
        d[i] = viz[i] = 0;
    d[M] = 1;
    DFS(M);
    MAX = -1;
    for (i = 1; i <= n; i++)
        if (d[i] > MAX)
            MAX = d[i];
    fout << MAX;
    return 0;
}