#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < n; i++)
#define rep2(i, x, n) for (int i = x; i <= n; i++)
#define rep3(i, x, n) for (int i = x; i >= n; i--)
#define each(e, v) for (auto &e : v)
#define pb push_back
#define eb emplace_back
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define sz(x) (int)x.size()
using ll = long long;
using pii = pair<int, int>;
using pil = pair<int, ll>;
using pli = pair<ll, int>;
using pll = pair<ll, ll>;

template <typename T>
bool chmax(T &x, const T &y) {
    return (x < y) ? (x = y, true) : false;
}

template <typename T>
bool chmin(T &x, const T &y) {
    return (x > y) ? (x = y, true) : false;
}

template <typename T>
int flg(T x, int i) {
    return (x >> i) & 1;
}

template <typename T>
void print(const vector<T> &v, T x = 0) {
    int n = v.size();
    for (int i = 0; i < n; i++) cout << v[i] + x << (i == n - 1 ? '\n' : ' ');
    if (v.empty()) cout << '\n';
}

template <typename T>
void printn(const vector<T> &v, T x = 0) {
    int n = v.size();
    for (int i = 0; i < n; i++) cout << v[i] + x << '\n';
}

template <typename T>
int lb(const vector<T> &v, T x) {
    return lower_bound(begin(v), end(v), x) - begin(v);
}

template <typename T>
int ub(const vector<T> &v, T x) {
    return upper_bound(begin(v), end(v), x) - begin(v);
}

template <typename T>
void rearrange(vector<T> &v) {
    sort(begin(v), end(v));
    v.erase(unique(begin(v), end(v)), end(v));
}

template <typename T>
vector<int> id_sort(const vector<T> &v, bool greater = false) {
    int n = v.size();
    vector<int> ret(n);
    iota(begin(ret), end(ret), 0);
    sort(begin(ret), end(ret), [&](int i, int j) { return greater ? v[i] > v[j] : v[i] < v[j]; });
    return ret;
}

template <typename S, typename T>
pair<S, T> operator+(const pair<S, T> &p, const pair<S, T> &q) {
    return make_pair(p.first + q.first, p.second + q.second);
}

template <typename S, typename T>
pair<S, T> operator-(const pair<S, T> &p, const pair<S, T> &q) {
    return make_pair(p.first - q.first, p.second - q.second);
}

template <typename S, typename T>
istream &operator>>(istream &is, pair<S, T> &p) {
    S a;
    T b;
    is >> a >> b;
    p = make_pair(a, b);
    return is;
}

template <typename S, typename T>
ostream &operator<<(ostream &os, const pair<S, T> &p) {
    return os << p.first << ' ' << p.second;
}

struct io_setup {
    io_setup() {
        ios_base::sync_with_stdio(false);
        cin.tie(NULL);
        cout << fixed << setprecision(15);
    }
} io_setup;

const int inf = (1 << 30) - 1;
const ll INF = (1LL << 60) - 1;
const int MOD = 1000000007;
// const int MOD = 998244353;

template <bool directed = false>
struct Graph {
    struct edge {
        int to, id;
        edge(int to, int id) : to(to), id(id) {}
    };

    vector<vector<edge>> es;
    const int n;
    int m;

    vector<int> d, si;
    vector<bool> used;
    vector<int> ma;

    Graph(int n) : es(n), n(n), m(0), d(n), si(n), used(n, false), ma(n, 0) {}

    void add_edge(int from, int to) {
        es[from].emplace_back(to, m);
        if (!directed) es[to].emplace_back(from, m);
        m++;
    }

    void calc_depth(int now, int pre = -1) {
        if (pre == -1) d[now] = 0;
        for (auto &e : es[now]) {
            if (e.to != pre) d[e.to] = d[now] + 1, calc_depth(e.to, now);
        }
    }

    int calc_size(int now, int pre = -1) {
        si[now] = 1;
        for (auto &e : es[now]) {
            if (e != pre) si[now] += calc_size(e.to, now);
        }
        return si[now];
    }

    int farthest_point(int s) {
        calc_depth(s);
        int max_d = -1, t = -1;
        for (int i = 0; i < n; i++) {
            if (d[i] > max_d) max_d = d[i], t = i;
        }
        return t;
    }

    pair<int, pair<int, int>> diameter() {
        int a = farthest_point(0), b = farthest_point(a);
        return make_pair(d[b], make_pair(a, b));
    }

    vector<int> ret_path;

    bool detect_path(int now, int t, bool use_id = false, int pre = -1) {
        if (now == t) {
            if (!use_id) ret_path.push_back(now);
            return true;
        }
        for (auto &e : es[now]) {
            if (e.to == pre) continue;
            if (detect_path(e.to, t, use_id, now)) {
                ret_path.push_back(use_id ? e.id : now);
                return true;
            }
        }
        return false;
    }

    vector<int> find_path(int s, int t, bool use_id = false) {
        ret_path.clear();
        detect_path(s, t, use_id);
        reverse(begin(ret_path), end(ret_path));
        return ret_path;
    }

    void solve() {
        rep(i, n - 1) {
            int u, v;
            cin >> u >> v;
            u--, v--;
            add_edge(u, v);
        }
        auto [s, t] = diameter().second;
        vector<int> p = find_path(s, t);
        each(e, p) used[e] = true;
        each(e, p) ma[e] = dfs(e);
        int K = sz(p);
        vector<int> l(K - 1), r(K - 1);
        rep(i, K - 1) {
            if (i > 0) l[i] = l[i - 1];
            chmax(l[i], i + ma[p[i]]);
        }
        rep3(i, K - 2, 0) {
            if (i < K - 2) r[i] = r[i + 1];
            chmax(r[i], K - 2 - i + ma[i + 1]);
        }
        int ans = inf;
        rep(i, K - 1) {
            int x = max(l[i], r[i]);
            chmax(x, (l[i] + 1) / 2 + (r[i] + 1) / 2 + 1);
            chmin(ans, x);
            // cout << l[i] << ' ' << r[i] << ' ' << x << '\n';
        }
        cout << ans << '\n';
    }

    int dfs(int now, int pre = -1) {
        int ret = 0;
        each(e, es[now]) {
            if (used[e.to] || e.to == pre) continue;
            chmax(ret, dfs(e.to, now) + 1);
        }
        return ret;
    }
};

int main() {
    int N;
    cin >> N;

    Graph G(N);
    G.solve();
}