#include <fstream>
#include<vector>
#include<queue>
#include<vector>
using namespace std;

ifstream fin("darb.in");
ofstream fout("darb.out");

int n,i,a,b,aux,start;
vector<int> v[100005];
int freq[100005];
vector<int> ::iterator it;
queue<int> q;

int main()
{
    fin>>n;
    for(i=1;i<=n;++i)
    {
        fin>>a>>b;
        v[a].push_back(b);
        v[b].push_back(a);
    }
    q.push(1);
    freq[1]=1;
    while(!q.empty())
    {
        aux=q.front();
        q.pop();
        for(it=v[aux].begin(); it!=v[aux].end();++it)
        {
            if(!freq[*it])
            {
                q.push(*it);
                freq[*it]=1;
            }
        }
    }
    start=aux;
    q.push(aux);
    for(i=1;i<=n;++i)
    freq[i]=0;
    while(!q.empty())
    {
        aux=q.front();
        q.pop();
        for(it=v[aux].begin();it!=v[aux].end();++it)
        {
            if(!freq[*it])
            {
                q.push(*it);
                freq[*it]=freq[aux]+1;
            }
        }
    }
    fout<<freq[aux]+1;



    return 0;
}