#include<fstream>
#include<vector>
#include<queue>
using namespace std;
ifstream fin("darb.in");
ofstream fout("darb.out");
vector <int> v[100001];
queue <int> q;
int n, m, i, s, nr, a, b, last;
int viz[100001];


void bfs(int st){
    int i, j;
    for (i = 1; i <= n; i++)
        viz[i] = -1;
    viz[st] = 1; q.push(st);
    while (!q.empty()){
        int nod = q.front(); q.pop();
        for (i = 0; i < v[nod].size(); i++)
            if (viz[v[nod][i]] == -1){
                viz[v[nod][i]] = viz[nod] + 1;
                last = v[nod][i];
                q.push(v[nod][i]);
            }
    }
}

int main(){
    fin >> n;
    for (i = 1; i < n; i++){
        fin >> a >> b;
        v[a].push_back(b);
        v[b].push_back(a);
    }
    bfs(1);
    bfs(last);
    fout << viz[last] << '\n';
    fin.close();
    fout.close();
}