using System;
using static System.Console;
using System.Linq;
using System.Collections.Generic;

class Program
{
    static int NN => int.Parse(ReadLine());
    static int[] NMi => ReadLine().Split().Select(c => int.Parse(c) - 1).ToArray();
    static int[][] NMap(int n) => Enumerable.Repeat(0, n).Select(_ => NMi).ToArray();
    public static void Main()
    {
        Solve();
    }
    static void Solve()
    {
        var n = NN;
        var map = NMap(n - 1);
        var tree = new List<int>[n];
        for (var i = 0; i < n; ++i) tree[i] = new List<int>();
        foreach (var edge in map)
        {
            tree[edge[0]].Add(edge[1]);
            tree[edge[1]].Add(edge[0]);
        }
        var len1 = Len(n, tree, 0);
        var far = 0;
        var fari = 0;
        for (var i = 0; i < n; ++i) if (far < len1[i])
        {
            far = len1[i];
            fari = i;
        }
        var len2 = Len(n, tree, fari);
        WriteLine(n - 1 - len2.Max());
    }
    static int[] Len(int n, List<int>[] tree, int start)
    {
        var len = Enumerable.Repeat(n, n).ToArray();
        len[start] = 0;
        var q = new Queue<int>();
        q.Enqueue(start);
        while (q.Count > 0)
        {
            var cur = q.Dequeue();
            foreach (var next in tree[cur])
            {
                if (len[next] <= len[cur] + 1) continue;
                len[next] = len[cur] + 1;
                q.Enqueue(next);
            }
        }
        return len;
    }
}