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

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

void DFS1(int nod)
{
    for(vector<int>::iterator it=Graf[nod].begin();it!=Graf[nod].end();it++)
    {
        if(uz[*it]==0)
        {
            uz[*it]=1;
            d[*it]=d[nod]+1;
            if(d[*it]>Max)
            {
                Max=d[*it];
                last=*it;
            }
            DFS1(*it);
        }
    }
}

void DFS2(int nod)
{
    for(vector<int>::iterator it=Graf[nod].begin();it!=Graf[nod].end();it++)
    {
        if(uz[*it]==1)
        {
            uz[*it]=0;
            d[*it]=d[nod]+1;
            if(d[*it]>Max)
            {
                Max=d[*it];
                last=*it;
            }
            DFS2(*it);
        }
    }
}

int main()
{
    Citire();
    uz[x]=d[x]=1;
    DFS1(x);

    uz[last]=d[last]=1;
    DFS2(last);
    ofstream f("darb.out");
    f<<Max;
}