#include <bits/stdc++.h>

using namespace std;

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

int n;
vector <int> ad[100005];
int d[100005], viz[100005];

void DFS(int nod)
{
    viz[nod] = 1;
    for(int e : ad[nod])
        if(viz[e] == 0)
        {
            d[e] = d[nod] + 1;
            DFS(e);
        }
}

int main()
{
    int x, y;
    fin >> n;
    for(int i = 1; i < n; i++)
    {
        fin >> x >> y;
        ad[x].push_back(y);
        ad[y].push_back(x);
    }
    DFS(1);
    x = 1;
    for(int i = 2; i <= n; i++)
        if(d[i] > d[x])
            x = i;
    for(int i = 1; i <= n; i++)
        d[i] = viz[i] = 0;
    DFS(x);
    x = 1;
    for(int i = 2; i <= n; i++)
        if(d[i] > d[x])
            x = i;
    fout << d[x] + 1 << '\n';
    return 0;
}