#include <iostream>
#include <fstream>
#include <vector>
#include <queue>
#include <algorithm>
using namespace std;
int n,apar1[100014],apar2[100014],nod1,sol=-1;
vector<int> v[100014];
void bfs (int nod, int apar[])
{
    int i;
    queue<int> q;
    q.push(nod);
    while (!q.empty())
    {
        nod=q.front();
        q.pop();
        for (i=0;i<v[nod].size();i++)
            if (apar[v[nod][i]]==0 || apar[v[nod][i]]>apar[nod]+1)
            {
                apar[v[nod][i]]=apar[nod]+1;
                q.push(v[nod][i]);
            }
    }
}
int main()
{
    int i,x,y;
    fstream f,g;
    f.open("darb.in",ios::in);
    g.open("darb.out",ios::out);
    f>>n;
    for (i=1;i<n;i++)
    {
        f>>x>>y;
        v[x].push_back(y);
        v[y].push_back(x);
    }
    bfs(1,apar1);
    for (i=1;i<=n;i++)
        if (sol<apar1[i])
        {
            sol=apar1[i];
            nod1=i;
        }
    bfs(nod1,apar2);
    sol=-1;
    for (i=1;i<=n;i++)
        sol=max(sol,apar2[i]);
    g<<sol+1;
}