import java.util.*;
import java.io.*;

public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner();
        int n = sc.nextInt();
        ArrayList<ArrayList<Integer>> graph = new ArrayList<>();
        for (int i = 0; i < n; i++) {
            graph.add(new ArrayList<>());
        }
        for (int i = 0; i < n - 1; i++) {
            int a = sc.nextInt() - 1;
            int b = sc.nextInt() - 1;
            graph.get(a).add(b);
            graph.get(b).add(a);
        }
        PriorityQueue<Path> queue = new PriorityQueue<>();
        queue.add(new Path(0, 0));
        int[] costs = new int[n];
        int max = 0;
        int maxIdx = 0;
        for (int i = 0; i < 2; i++) {
            Arrays.fill(costs, Integer.MAX_VALUE);
            while (queue.size() > 0) {
                Path p = queue.poll();
                if (costs[p.idx] <= p.value) {
                    continue;
                }
                costs[p.idx] = p.value;
                for (int x : graph.get(p.idx)) {
                    queue.add(new Path(x, p.value + 1));
                }
            }
            for (int j = 0; j < n; j++) {
                if (max < costs[j]) {
                    max = costs[j];
                    maxIdx = j;
                }
            }
            queue.add(new Path(maxIdx, 0));
        }
        System.out.println((n - 1) * 2 - max);
    }
    
    
    static class Path implements Comparable<Path> {
        int idx;
        int value;
        
        public Path(int idx, int value) {
            this.idx = idx;
            this.value = value;
        }
        
        public int compareTo(Path another) {
            return value - another.value;
        }
    }
}
class Scanner {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    StringTokenizer st = new StringTokenizer("");
    
    public Scanner() throws Exception {
        
    }
    
    public int nextInt() throws Exception {
        return Integer.parseInt(next());
    }
    
    public long nextLong() throws Exception {
        return Long.parseLong(next());
    }
    
    public double nextDouble() throws Exception {
        return Double.parseDouble(next());
    }
    
    public String nextLine() throws Exception {
        return br.readLine();
    }
    
    public String next() throws Exception {
        if (!st.hasMoreTokens()) {
            st = new StringTokenizer(br.readLine());
        }
        return st.nextToken();
    }
}