#include <bits/stdc++.h>

using namespace std;
ifstream in("darb.in");
ofstream out("darb.out");
const int nx = 100001;
bitset < nx > viz;
int dist[nx];
vector < int > v[nx];
int mx = 0, nod, rad;
int n,m,i,j;
queue < int > q;
void bfs (int start)
{
    memset(dist,0,sizeof(dist));
    dist[start]=1;
    q.push(start);
    while(!q.empty())
    {
        int x = q.front();
        q.pop();
        for(vector < int > :: iterator it = v[x].begin(); it!=v[x].end(); it++)
            if(dist[*it]==0)
            {
                dist[*it]=dist[x]+1;
                q.push(*it);
            }
    }
}
int main()
{
    in>>n;
    for(int t = 1; t<n; t++)
    {
        in>>i>>j;
        v[i].push_back(j);
        v[j].push_back(i);
    }
    bfs(1);
    for(int i=1; i<=n; i++)
        if(dist[i]>mx)
        {
            mx = dist[i];
            nod = i;
        }
    bfs(nod);
    mx = 0;
    for(int i=1; i<=n; i++)
        if(dist[i]>mx)
            mx = dist[i];
    out<<mx;
    return 0;
}