#include <fstream>
#include <vector>
#include <algorithm>
#include <queue>
using namespace std;
ifstream fin("darb.in");
ofstream fout("darb.out");
const int NMAX= 100000;
vector <int>G[NMAX+5];
queue <int>q;
int viz1[NMAX+5];
int viz2[NMAX+5];
void BFS1(int nod)
{
    int i;
    viz1[nod]=1;
    q.push(nod);
    while(!q.empty())
    {
        nod=q.front();
        q.pop();
        for(i=0;i<G[nod].size();i++)
        {
            if(viz1[G[nod][i]]==0)
            {
                viz1[G[nod][i]]=viz1[nod]+1;
                q.push(G[nod][i]);
            }
        }
    }
}
void BFS2(int nod)
{
    int i;
    viz2[nod]=1;
    q.push(nod);
    while(!q.empty())
    {
        nod=q.front();
        q.pop();
        for(i=0;i<G[nod].size();i++)
        {
            if(viz2[G[nod][i]]==0)
            {
                viz2[G[nod][i]]=viz2[nod]+1;
                q.push(G[nod][i]);
            }
        }
    }
}
int main()
{
    int n, i, x, y;
    fin>>n;
    for(i=1;i<=n;i++)
    {
        fin>>x>>y;
        G[x].push_back(y);
        G[y].push_back(x);
    }
    BFS1(1);
    int nod, viz=0;
    for(i=1;i<=n;i++)
    {
        if(viz<viz1[i])
            {
                viz=viz1[i];
                nod=i;
            }

    }
    BFS2(nod);
    fout<<*max_element(viz2+1, viz2+n+1)<<"\n";


    return 0;
}