/*
ID: Sho10
LANG: C++
TASK:
*/
#include <bits/stdc++.h> //JuniorMonster a.k.a Sho10
#define ll long long int
#pragma GCC optimize("O3")
#pragma GCC optimize("Ofast")
#define all(a) (a).begin(), (a).end()
#define sz size
#define f first
#define s second
#define pb push_back
#define er erase
#define in insert
#define mp make_pair
#define pi pair
#define rc(s) return cout<<s,0
#define endl '\n'
#define mod 1000000007
#define PI 3.14159265359
#define CODE_START  ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
using namespace std;
ll n,dist[100005],root=1,x,y;
vector<ll>v[100005];
bitset<100005>viz;
queue<ll>q;
int32_t main(){
    ifstream cin("darb.in");
    ofstream cout("darb.out");
    cin>>n;
    for(ll i=0;i<n;i++)
    {
        cin>>x>>y;
        v[x].pb(y);
        v[y].pb(x);
    }
    root=1;
    viz[root]=1;
    dist[root]=1;
    q.push(root);
    while(!q.empty()){
        x=q.front();
        viz[x]=1;
        for(ll i=0;i<v[x].size();i++)
            if(viz[v[x][i]]==0){
                q.push(v[x][i]);
                dist[v[x][i]]=dist[x]+1;
            }
            q.pop();
    }
    for(ll i=1;i<=n;i++)
    if(dist[i]>dist[root]){
        root=i;
    }
    for(ll i=1;i<=n;i++)
        viz[i]=0;
    q.push(root);
    dist[root]=1;
    viz[root]=1;
    while(!q.empty()){
        x=q.front();
        viz[x]=1;
        for(ll i=0;i<v[x].size();i++)
        if(viz[v[x][i]]==0){
            q.push(v[x][i]);
            dist[v[x][i]]=dist[x]+1;
        }
        q.pop();
    }
    cout<<dist[x]<<endl;
}