#include<fstream>
#include<vector>
#include<queue>
#define NMAX 100010

using namespace std;

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

vector<int> a[NMAX];
queue<int> q;
int n, ultim, vz[NMAX];

void Citeste()
{
    int i, x, y;

    f>>n;
    for (i=1; i<n; ++i)
    {
        f>>x>>y;
        a[x].push_back(y);
        a[y].push_back(x);
    }
}

void BFS(int start)
{
    int i, nod, r;

    q.push(start); vz[start]=1;
    while (!q.empty())
    {
        ultim=nod=q.front(); q.pop();

        for (i=0; i<a[nod].size(); ++i)
        {
            r=a[nod][i];
            if (!vz[r])
            {
                vz[r]=vz[nod]+1;
                q.push(r);
            }
        }
    }
}

void Initializeaza()
{
    int i;
    for (i=1; i<=n; ++i) vz[i]=0;
}

void Scrie()
{
    int i;
    g<<vz[ultim]<<"\n";
}

int main()
{
    Citeste();

    BFS(1);

    Initializeaza();

    BFS(ultim);

    Scrie();

    f.close();
    g.close();
    return 0;
}