using System;
using System.Collections.Generic;
using System.Linq;
using static System.Console;
using static System.Convert;
using static System.Math;
//using Debug;
//using static System.Globalization.CultureInfo;
//using Edge = Pair<long, int>;
using System.Text;
class Program
{
    static void Main(string[] args)
    {
        Solve();
        //WriteLine(Solve());
    }
    static int[] nk;
    static List<int>[] adj;
    static void Solve()
    {
        nk = Input.ar;
        adj = Enumerable.Repeat(0, nk[0]).Select(_ => new List<int>()).ToArray();
        var ab = Input.ar2D(nk[0] - 1);
        for (var i=0;i<nk[0]-1;i++)
        {
            ab[i][0]--;ab[i][1]--;
            adj[ab[i][0]].Add(ab[i][1]);
            adj[ab[i][1]].Add(ab[i][0]);
        }
        var res = int.MaxValue;
        if (nk[1] % 2 == 0)
            for (var i = 0; i < nk[0]; i++)
                res = Min(res, bfs(i));
        else foreach (var e in ab)
                res = Min(res, bfs(e[0], e[1]));

        WriteLine(res);
    }
    static int bfs(params int[] st)
    {
        var dist = Enumerable.Repeat(-1, nk[0]).ToArray();
        var que = new Queue<int>();
        foreach (var v in st)
        {
            dist[v] = 0;
            que.Enqueue(v);
        }
        while (que.Any())
        {
            var p = que.Dequeue();
            foreach (var ad in adj[p])
            {
                if (dist[ad] != -1||dist[p]+1>nk[1]/2) continue;
                dist[ad] = dist[p] + 1;
                que.Enqueue(ad);
            }
        }
        return dist.Count(v => v == -1);
    }
}

public class Input
{
    public static string read => ReadLine().Trim();
    public static int[] ar => read.Split(' ').Select(int.Parse).ToArray();
    public static int num => ToInt32(read);
    public static long[] arL => read.Split(' ').Select(long.Parse).ToArray();
    public static long numL => ToInt64(read);
    public static char[][] gred(int h)
        => Enumerable.Repeat(0, h).Select(_ => read.ToCharArray()).ToArray();
    public static int[] ar1D(int n)
        => Enumerable.Repeat(0, n).Select(_ => num).ToArray();
    public static long[] arL1D(int n)
        => Enumerable.Repeat(0, n).Select(_ => numL).ToArray();
    public static string[] strs(int n)
        => Enumerable.Repeat(0, n).Select(_ => read).ToArray();
    public static int[][] ar2D(int n)
        => Enumerable.Repeat(0, n).Select(_ => ar).ToArray();
    public static long[][] arL2D(int n)
        => Enumerable.Repeat(0, n).Select(_ => arL).ToArray();
    public static T getValue<T>(string g)
    {
        var t = typeof(T);
        if (t == typeof(int))
            return (T)(object)int.Parse(g);
        if (t == typeof(long))
            return (T)(object)long.Parse(g);
        if (t == typeof(string))
            return (T)(object)g;
        if (t == typeof(char))
            return (T)(object)char.Parse(g);
        if (t == typeof(double))
            return (T)(object)double.Parse(g);
        if (t == typeof(bool))
            return (T)(object)bool.Parse(g);
        return default(T);
    }
    public static string[] Make<T1, T2>(out T1 v1, out T2 v2)
    {
        var r = read.Split(' ');
        v1 = getValue<T1>(r[0]);
        v2 = getValue<T2>(r[1]);
        return r;
    }
    public static string[] Make<T1, T2, T3>(out T1 v1, out T2 v2, out T3 v3)
    {
        var r = Make(out v1, out v2);
        v3 = getValue<T3>(r[2]);
        return r;
    }
    public const long Inf = (long)1e18;
    public const double eps = 1e-6;
    public const string Alfa = "abcdefghijklmnopqrstuvwxyz";
    public const int MOD = 1000000007;
}


Measured memory_bytes: 40392