#include <iostream>
#include <fstream>
#include <vector>
#include <queue>
#define NMAX 100005
using namespace std;

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

queue<int> q;
vector<int> v[NMAX];
int n;
bool ap[NMAX];
int dist[NMAX];
void BFS(int nod)
{
    ap[nod]=true;
    dist[nod]=0;
    q.push(nod);
    while(!q.empty()){
        int fata=q.front();
        q.pop();
        for(auto i:v[fata]){
            if(!ap[i]){
                q.push(i);
                ap[i]=true;
                dist[i]=dist[fata]+1;
            }
        }
    }
}
int main()
{
    int x,y;
    in>>n;
    for(int i=1;i<n;++i){
        in>>x>>y;
        v[x].push_back(y);
        v[y].push_back(x);
    }
    BFS(1);
    int maxim=-1,indice;
    for(int i=1;i<=n;++i)
        if(dist[i]>maxim){
            maxim=dist[i];
            indice=i;
        }
    for(int i=1;i<=n;++i){
        dist[i]=0;
        ap[i]=false;
    }
    BFS(indice);
    maxim=-1;
    for(int i=1;i<=n;++i)
        if(dist[i]>maxim){
            maxim=dist[i];
            indice=i;
        }
    out<<maxim+1;
    return 0;
}