#include <iostream>
#include <fstream>
#include <vector>
#define NMax 100001
using namespace std;
vector<int> Graf[NMax];
bool uz[NMax];
int d[NMax],x,y,Max,N,last;

void Citire()
{
    ifstream g("darb.in");
    g>>N;
    for(int i=1;i<=N;i++)
    {
        g>>x>>y;
        x--;
        y--;
        Graf[x].push_back(y);
        Graf[y].push_back(x);
    }
}

void DFS(int nod)
{
    for(vector<int>::iterator it=Graf[nod].begin();it!=Graf[nod].end();it++)
    {
        if(uz[*it]==false)
        {
            uz[*it]=true;
            d[*it]=d[nod]+1;
            if(d[*it]>Max)
            {
                Max=d[*it];
                last=*it;
            }
            DFS(*it);
        }
    }
}

int main()
{
    Citire();
    uz[x]=true;
    d[x]=1;
    DFS(x);
    uz[last]=true;
    d[last]=1;
    DFS(last);
    ofstream f("darb.out");
    f<<Max;
}