#include <fstream>
#include <vector>
#define N 100002
#define INF 2000000000
#include <deque>
#include <bitset>

using namespace std;
ifstream f("darb.in");
ofstream g("darb.out");

vector <int> graph[N];
int last,dr[N];
deque <int> q;

void bf(int nod)
{
    q.push_back(nod);
    dr[nod]=1;
    while(!q.empty())
    {
        nod=q.front();
        q.pop_front();
        for(int i=0;i<graph[nod].size();++i)
        {
            int vee=graph[nod][i];
            if(dr[vee]>dr[nod]+1)
            {
               dr[vee]=dr[nod]+1;
               last=vee;
               q.push_back(vee);
            }
        }
    }
}
int main()
{
    int n,x,y;
    f>>n;
    for(int i=1;i<n;++i)
        f>>x>>y,graph[x].push_back(y),graph[y].push_back(x);
    for(int i=1;i<=n;++i) dr[i]=INF;
    bf(1);
    for(int i=1;i<=n;++i) dr[i]=INF;
    bf(last);
    g<<dr[last]<<'\n';
    f.close();
    g.close();
    return 0;
}