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

int main() {
    int n;
    cin >> n;
    vector<vector<int>> adj(n);
    for (int i = 0; i < n - 1; i++) {
        int a, b;
        cin >> a >> b;
        a--, b--;
        adj[a].push_back(b);
        adj[b].push_back(a);
    }

    vector<int> ds(n);
    function<void(int, int, int)> dfs = [&](int v, int p, int d) {
        ds[v] = d;
        for (int s : adj[v]) {
            if (s != p) {
                dfs(s, v, d + 1);
            }
        }
    };
    dfs(0, -1, 0);
    int k = max_element(ds.begin(), ds.end()) - ds.begin();
    dfs(k, -1, 0);
    int diameter = *max_element(ds.begin(), ds.end());
    cout << n - 1 - diameter << endl;
}