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

using namespace std;

template<typename T = int>
struct Edge {
    int from, to;
    T cost;
    int idx;

    Edge() = default;

    Edge(int from, int to, T cost = 1, int idx = -1) : from(from), to(to), cost(cost), idx(idx) {}

    operator int() const { return to; }
};

template<typename T = int>
struct Graph {
    vector<vector<Edge<T>>> g;
    int es;

    Graph() = default;

    explicit Graph(int n) : g(n), es(0) {}

    size_t size() const {
        return g.size();
    }

    void add_directed_edge(int from, int to, T cost = 1) {
        g[from].emplace_back(from, to, cost, es++);
    }

    void add_edge(int from, int to, T cost = 1) {
        g[from].emplace_back(from, to, cost, es);
        g[to].emplace_back(to, from, cost, es++);
    }

    void read(int M, int padding = -1, bool weighted = false, bool directed = false) {
        for (int i = 0; i < M; i++) {
            int a, b;
            cin >> a >> b;
            a += padding;
            b += padding;
            T c = T(1);
            if (weighted) cin >> c;
            if (directed) add_directed_edge(a, b, c);
            else add_edge(a, b, c);
        }
    }
};

template<typename T = int>
struct TreeDiameter : Graph<T> {
public:
    using Graph<T>::Graph;
    using Graph<T>::g;
    vector<Edge<T>>
            path;

    T build() {
        to.assign(g.size(), -1);
        auto p = dfs(0, -1);
        auto q = dfs(p.second, -1);

        int now = p.second;
        while (now != q.second) {
            for (auto &e : g[now]) {
                if (to[now] == e.to) {
                    path.emplace_back(e);
                }
            }
            now = to[now];
        }
        return q.first;
    }

    explicit TreeDiameter(const Graph<T> &g) : Graph<T>(g) {}

private:
    vector<int> to;

    pair<T, int> dfs(int idx, int par) {
        pair<T, int> ret(0, idx);
        for (auto &e : g[idx]) {
            if (e.to == par) continue;
            auto cost = dfs(e.to, idx);
            cost.first += e.cost;
            if (ret < cost) {
                ret = cost;
                to[idx] = e.to;
            }
        }
        return ret;
    }
};

int main() {
    int n;
    cin >> n;
    TreeDiameter<int> g(n);
    g.read(n - 1, -1);
    cout << n - 1 - g.build() << endl;
    return 0;
}