#include <fstream>
#include <queue>
#include <vector>
#include <cstring>
using namespace std;
ifstream f("darb.in");
ofstream g("darb.out");
int nr[100005],x,viz[100005],n,i,k,m;
queue<int> q;
vector<int> a[100005];
int main()
{
    f>>n;
    for(i=1;i<=n-1;i++)
    {
        f>>k>>m;
        a[k].push_back(m);
        a[m].push_back(k);
    }
    q.push(1);
    viz[1]=1;
    while(!q.empty())
    {
        x=q.front();
        q.pop();
        for(vector<int>::iterator it=a[x].begin();it!=a[x].end();it++)
        {
            if(!viz[*it])
            {
                viz[*it]++;
                q.push(*it);
            }
        }
    }
    memset(viz,0,sizeof(viz));
    q.push(x);
    viz[x]=1;
    nr[x]++;
    while(!q.empty())
    {
        x=q.front();
        q.pop();
        for(vector<int>::iterator it=a[x].begin();it!=a[x].end();it++)
        {
            if(!viz[*it])
            {
                viz[*it]++;
                q.push(*it);
                nr[*it]=nr[x]+1;
            }
        }
    }
    g<<nr[x]<<'\n';
    return 0;
}