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

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    int n;
    cin >> n;
    vector<vector<int>> g(n);
    for(int i = 1; i < n; i++){
        int u, v;
        cin >> u >> v;
        g[--u].push_back(--v);
        g[v].push_back(u);
    }
    auto bfs = [&](int from){
        queue<int> nxt;
        vector<int> dist(n, 1 << 30);
        dist[from] = 0;
        nxt.push(from);
        while(!nxt.empty()){
            int v = nxt.front();
            nxt.pop();
            for(auto &u : g[v]){
                if(dist[v] + 1 >= dist[u]) continue;
                dist[u] = dist[v] + 1;
                nxt.push(u);
            }
        }
        return dist;
    };
    auto dist = bfs(0);
    dist = bfs(max_element(dist.begin(), dist.end()) - dist.begin());
    cout << 2 * (n - 1) - *max_element(dist.begin(), dist.end()) << '\n';
}