#include <bits/stdc++.h>
using namespace std;
 
typedef long long ll;
typedef vector<int> vi;
typedef pair<int, int> pi;
#define pb push_back
#define mp make_pair
#define f first
#define s second

vector<vi> adj(100005);
int visited[100005];
int maxe = 0;

void dfs(int x, int last_dist){
    //cout << x << ' ';
    last_dist++;
    visited[x] = 1;
    maxe = max(maxe, last_dist);
    for(auto i : adj[x]){
        if(!visited[i]){
            dfs(i, last_dist);
        }
    }
}

void solve(){
    int n;
    cin >> n;
    for(int i = 0; i < n-1; i++){
        int a, b;
        cin >> a >> b;
        adj[a].pb(b);
        adj[b].pb(a);
    }
    vi distances;
    for(auto i : adj[1]){
        memset(visited, 0, sizeof(visited));
        visited[1] = 1;
        dfs(i, 1);
        distances.pb(maxe);
        maxe = 0;
    }
    sort(distances.begin(), distances.end(), greater<int>());
    /*for(auto i : distances)
        cout << i << ' ';
    cout << '\n';*/
    if(distances.size() == 1)
        cout << distances[0] << '\n';
    else
        cout << distances[0] + distances[1] - 1 << '\n';
}  
 
int main(){
    freopen("darb.in", "r", stdin);
    freopen("darb.out", "w", stdout);
    ios::sync_with_stdio(0); cin.tie(0);
    int t = 1;
    //cin >> t;
    while(t--){
        solve();
    }
}