#include <fstream>
#include <vector>
#include <queue>
#include <cstring>
using namespace std;
ifstream fin("darb.in");
ofstream fout("darb.out");
queue<int>Q;
vector<int>H[100001];
bool viz[100001];
int last,diametru,dist[100001];
void bfs(int start)
{
    memset(viz,0,sizeof(viz));
    memset(dist,0,sizeof(dist));
    viz[start]=1;
    Q.push(start);
    dist[start]=1;
    while(Q.size())
    {
        int a=Q.front();Q.pop();
        for(vector<int>::iterator it=H[a].begin();it!=H[a].end();it++)
        {
            if(viz[*it]==0)
            {
                dist[*it]=dist[a]+1;
                last=*it;
                diametru=dist[*it];
                viz[*it]=1;
                Q.push(*it);
            }
        }
    }
}
int main()
{
    int n,i,a,b;
    fin>>n;
    for(i=1;i<n;i++)
    {
        fin>>a>>b;
        H[a].push_back(b);
        H[b].push_back(a);
    }
    bfs(1);
    bfs(last);
    fout<<diametru;
}