#include <bits/stdc++.h>
using namespace std;

ifstream f("darb.in");
ofstream g("darb.out");
///1A
int n;
vector < int > v[100005];
int a,b;
int viz1[100005],viz2[100005];
int dist[100005],dmax[100005];
queue < int > q;
int ultnod,nod;

int main()
{
    f >> n;
    for (int i=1;i<n;i++) {
        f >> a >> b;
        v[a].push_back(b);
        v[b].push_back(a);
    }
    q.push(1);
    dist[1]=1;
    viz1[1]=1;
    while (q.empty()==0) {
        nod = q.front();
        q.pop();
        for (auto nodtoviz:v[nod]) {
            if (viz1[nodtoviz]==0) {
                viz1[nodtoviz] = 1;
                dist[nodtoviz] = dist[nod] + 1;
                ultnod = nodtoviz;
                q.push(nodtoviz);
            }
        }
    }
    q.push(ultnod);
    dmax[ultnod] = 1;
    viz2[ultnod] = 1;
    while (q.empty()==0) {
        nod = q.front();
        q.pop();
        for (auto nodtoviz:v[nod]) {
            if (viz2[nodtoviz]==0) {
                viz2[nodtoviz] = 1;
                dmax[nodtoviz] = dmax[nod] + 1;
                ultnod = nodtoviz;
                q.push(nodtoviz);
            }
        }
    }
    g << dmax[ultnod];
    return 0;
}