#include <iostream>
#include <algorithm>
#include <vector>
#include <queue>

using namespace std;

void solve() {
    int n;
    cin >> n;

    vector<vector<int>> graph(n);
    for (int i = n - 1; i--;) {
        int u, v;
        cin >> u >> v;
        --u, --v;
        graph[u].push_back(v);
        graph[v].push_back(u);
    }

    auto bfs = [&](int r) {
        vector<int> ds(n, -1);
        ds[r] = 0;
        queue<int> que;
        que.push(r);

        while (!que.empty()) {
            auto v = que.front();
            que.pop();

            for (auto u : graph[v]) {
                if (ds[u] != -1) continue;
                ds[u] = ds[v] + 1;
                que.push(u);
            }
        }
        return ds;
    };

    auto ds = bfs(0);
    int r = max_element(ds.begin(), ds.end()) - ds.begin();
    ds = bfs(r);
    cout << (n - 1) * 2 - *max_element(ds.begin(), ds.end()) << "\n";
}

int main() {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);

    solve();

    return 0;
}