#include <bits/stdc++.h>
using namespace std;
vector <int> v[100005];
deque <int> Q;
int n, x, i, y, ct, poz1, a[100005], poz2;
bool viz[100005];
void BFS(int x, int & ct, int & poz)
{
    Q.push_front(x);
    viz[x] = true;
    a[x] = 1;
    while(!Q.empty())
    {
        int k = Q.front();
        ct = a[k];
        poz = k;
        for(int i = 0;i < v[k].size();i++)
            if(viz[v[k][i]] == false)
            {
                viz[v[k][i]] = true;
                a[v[k][i]] = a[k] + 1;
                Q.push_back(v[k][i]);
            }
        Q.pop_front();
    }
    memset(viz, 0, sizeof(viz));
}
int main()
{
    ifstream f("darb.in");
    ofstream g("darb.out");
    f >> n;
    for(i = 1;i <= n - 1;i++)
    {
        f >> x >> y;
        v[x].push_back(y);
        v[y].push_back(x);
    }
    ct = 0;
    BFS(1, ct, poz1);
    ct = 1;
    BFS(poz1, ct, poz2);
    g << ct;
    return 0;
}