#include<fstream>
#include<vector>
#include<queue>
#include<cstring>
using namespace std;
ifstream f("darb.in");
ofstream g("darb.out");
int n, last, diametru, contor[100001];
bool viz[100001];
vector <int> v[100001];
queue <int> c;
void citire()
{
    int i, j, x, y;
    f>>n;
    for(i=1;i<=n-1;i++)
    {
        f>>x>>y;
        v[x].push_back(y);
        v[y].push_back(x);
    }
}
void bfs(int x)
{
    int i, p;
    viz[x]=1;
    contor[x]=1;
    memset(viz,false,sizeof(viz));
    c.push(x);
    while(!c.empty())
    {
        p=c.front();
        for(i=0;i<v[p].size();i++)
        {
            if(!viz[v[p][i]])
            {
                viz[v[p][i]]=1;
                c.push(v[p][i]);
                contor[v[p][i]]=contor[p]+1;
                last=v[p][i];
                diametru=contor[v[p][i]];
            }
        }
        c.pop();
    }
}
int main()
{
    citire();
    bfs(1);
    bfs(last);
    g<<diametru;
    f.close();
    g.close();
    return 0;
}