#include <bits/stdc++.h>
#define rep(i,n) for(int i = 0; i < (n); i++)
using namespace std;
using ll = long long;
using ld = long double;

template < class T > class tree_diameter {
  public:
    T diameter;
    vector<int> path, parent;
    vector< T > dist;

    tree_diameter(const vector<vector<pair<int,T>>> &tree) {
        int n = tree.size();
        parent.assign(n, -1);
        dist.resize(n);

        dist[0] = T(0); dfs(tree, 0, -1);
        int u = max_element(dist.begin(), dist.end()) - dist.begin();
        dist[u] = T(0); dfs(tree, u, -1);
        int v = max_element(dist.begin(), dist.end()) - dist.begin();
        diameter = dist[v];
        while(v != -1) path.push_back(v), v = parent[v];
    }

    void dfs(const vector<vector<pair<int,T>>> &tree, int v, int p) {
        parent[v] = p;
        for(auto [to, cost] : tree[v]) if(to != p) dist[to] = dist[v] + cost, dfs(tree, to, v);
    }
};

int main(){
    cin.tie(0);
    ios::sync_with_stdio(0);
    
    int N; cin >> N;
    vector<vector<pair<int,int>>> G(N);
    rep(i,N-1) {
        int u,v; cin >> u >> v; u--; v--;
        G[u].push_back({v, 1});
        G[v].push_back({u, 1});
    }

    cout << 2 * (N - 1) - tree_diameter(G).diameter << endl;
}