#include<fstream>
#include<algorithm>
#include<queue>

using namespace std;
ifstream fin("darb.in");
ofstream fout("darb.out");
int n,m,k,x,y,i,sol;
int viz[100009];
queue <int>q;

vector <int> v[100009];

void bfs(int start)
{
    q.push(start);
    int i,nod;
    while(!q.empty())
    {
        nod=q.front();
        sol=nod;
        q.pop();
        for(i=0;i<v[nod].size();i++)
        {
            if(viz[v[nod][i]]==0)
            {
                viz[v[nod][i]]=1;
                q.push(v[nod][i]);
            }
        }

    }
}
void bfs1(int start)
{
    q.push(start);
    int i,nod;
    while(!q.empty())
    {
        nod=q.front();
        sol=nod;
        q.pop();
        for(i=0;i<v[nod].size();i++)
        {
            if(viz[v[nod][i]]==0)
            {
                viz[v[nod][i]]=viz[nod]+1;
                q.push(v[nod][i]);
            }
        }

    }
}
int main()
{
    fin>>n;
    for(i=1;i<=n;i++)
    {
        fin>>x>>y;
        v[x].push_back(y);
        v[y].push_back(x);
    }
    viz[1]=1;
    bfs(1);
    for(i=1;i<=n;i++) viz[i]=0;
    viz[sol]=1;
    bfs1(sol);
    int maxim=0;
    for(i=1;i<=n;i++)
    {
        maxim=max(maxim,viz[i]);
    }
    fout<<maxim<<"\n";
}