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

struct Edge {
    int u;
    int v;
    int cost;
    Edge(int a, int b, int c) : u(a), v(b), cost(c) {

    }
};
using Graph = vector<vector<Edge>>;

vector<int> dp;
int max_, max_2;

void dfs(const Graph& G, int v, int p, int x, bool flag) {
    if (x == v) flag = false;

    for (auto nv : G[v]) {
        if (nv.v == p) continue;
        dfs(G, nv.v, v, x, flag);
    }

    if (flag) {
        int max1 = 0, max2 = 0;
        for (auto c : G[v]) {
            if (c.v == p) continue;
            if (max1 < dp[c.v]) {
                max2 = max1;
                max1 = dp[c.v];
            }
            else if (max2 < dp[c.v]) {
                max2 = dp[c.v];
            }
        }
        max_ = max(max_, max1 + max2 + 1);
        dp[v] = max1 + 1;
    }
    else {
        int max1 = 0, max2 = 0;
        for (auto c : G[v]) {
            if (c.v == p) continue;
            if (max1 < dp[c.v]) {
                max2 = max1;
                max1 = dp[c.v];
            }
            else if (max2 < dp[c.v]) {
                max2 = dp[c.v];
            }
        }
        max_2 = max(max_2, max1 + max2 + 1);
        dp[v] = max1 + 1;
    }

    if (x == v) dp[v] = 0;
}

void dfs2(const Graph& G, int v, int p) {
    for (auto nv : G[v]) {
        if (nv.v == p) continue;
        dfs2(G, nv.v, v);
    }
;
    for (auto c : G[v]) {
        if (c.v == p) continue;
        dp[v] = max(dp[v], dp[c.v] + 1);
    }
}

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

    Graph G(N);
    for (int i = 0; i < N - 1; i++) {
        int a, b;
        cin >> a >> b;
        G[a - 1].emplace_back(a - 1, b - 1, 1);
        G[b - 1].emplace_back(b - 1, a - 1, 1);
    }

    bool flag = true;
    for (int i = 0; i < N; i++) {
        if (G[i].size() >= 3) flag = false;
    }
    if (flag) {
        cout << N << endl;
        return 0;
    }

    int ans = 0;

    for (int i = 0; i < N; i++) {
        dp.assign(N, 0);
        max_ = 0;
        max_2 = 0;
        dfs(G, 0, -1, i, true);
        ans = max(ans, max_ + max_2);
    }

    cout << ans << endl;
}