#include <fstream>
#include <list>
using namespace std;

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

bool *v;
int x,poz;
list<int> *l;

void bk(int i, int s)
{
    v[i]=0;
    if(s>x)
    {
        x=s;
        poz=i;
    }
    for(list<int>::iterator j=l[i].begin();j!=l[i].end();++j)
        if(v[*j])
            bk(*j,s+1);
}

int main()
{
    int n,i,a,b;
    fin>>n;
    v=new bool[n+1];
    l=new list<int>[n+1];
    for(i=1;i<=n;++i)
    {
        fin>>a>>b;
        l[a].push_back(b);
        l[b].push_back(a);
    }
    for(i=1;i<=n;v[i]=1,++i);
    bk(1,1);
    for(i=1;i<=n;v[i]=1,++i);
    bk(poz,1);
    fout<<x;
}