using System;
using System.Collections;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Numerics;
using System.Text;
using System.Threading.Tasks;

namespace AtCorder
{
	public class Program
	{
		static void Main(string[] args)
		{
			var cin = new Scanner2();
			int n = cin.Int();
			int k = cin.Int();

			var ab = new Tuple<int, int>[n - 1];
			for (int i = 0; i < n - 1; i++) {
				int a = cin.Int() - 1;
				int b = cin.Int() - 1;
				ab[i] = new Tuple<int, int>(a, b);
			}

			var to = new List<int>[n];
			for (int i = 0; i < n; i++) {
				to[i] = new List<int>();
			}

			for (int i = 0; i < n - 1; i++) {
				int a = ab[i].Item1;
				int b = ab[i].Item2;
				to[a].Add(b);
				to[b].Add(a);
			}

			int ans = int.MaxValue;
			if (k % 2 == 0) {
				int d = k / 2;
				for (int i = 0; i < n; i++) {
					var ds = GetDistance(n, i, to);
					int count = ds.Where(x => x > d).Count();
					ans = Math.Min(ans, count);
				}
			} else {
				int d = (k - 1) / 2;
				for (int i = 0; i < n - 1; i++) {
					var ds = GetDistance(n, ab[i].Item1, ab[i].Item2, to);
					int count = ds.Where(x => x > d).Count();
					ans = Math.Min(ans, count);
				}
			}

			Console.WriteLine(ans);

		}

		private static int[] GetDistance(int n, int s, List<int>[] to)
		{
			var d = new int[n];
			for (int i = 0; i < n; i++) {
				d[i] = -1;
			}

			d[s] = 0;
			var q = new Queue<int>();
			q.Enqueue(s);
			while (q.Count > 0) {
				int cur = q.Dequeue();
				foreach (int next in to[cur]) {
					if (d[next] == -1) {
						d[next] = d[cur] + 1;
						q.Enqueue(next);
					}
				}
			}

			return d;
		}

		private static int[] GetDistance(int n, int a, int b, List<int>[] to)
		{
			var d = new int[n];
			for (int i = 0; i < n; i++) {
				d[i] = -1;
			}

			d[a] = 0;
			d[b] = 0;
			var q = new Queue<int>();
			q.Enqueue(a);
			q.Enqueue(b);
			while (q.Count > 0) {
				int cur = q.Dequeue();
				foreach (int next in to[cur]) {
					if (d[next] == -1) {
						d[next] = d[cur] + 1;
						q.Enqueue(next);
					}
				}
			}

			return d;
		}
	}

	public class Scanner2
	{
		private readonly char[] delimiter_ = new char[] { ' ' };
		private readonly string filePath_;
		private readonly Func<string> reader_;
		private string[] buf_;
		private int index_;

		public Scanner2(string file = "")
		{
			if (string.IsNullOrWhiteSpace(file)) {
				reader_ = Console.ReadLine;
			} else {
				filePath_ = file;
				var fs = new StreamReader(file);
				reader_ = fs.ReadLine;
			}
			buf_ = new string[0];
			index_ = 0;
		}

		public string Next()
		{
			if (index_ < buf_.Length) {
				return buf_[index_++];
			}

			string st = reader_();
			while (st == "") {
				st = reader_();
			}

			buf_ = st.Split(delimiter_, StringSplitOptions.RemoveEmptyEntries);
			if (buf_.Length == 0) {
				return Next();
			}

			index_ = 0;
			return buf_[index_++];
		}

		public int Int() => int.Parse(Next());
		public long Long() => long.Parse(Next());
		public double Double() => double.Parse(Next());

		public int[] ArrayInt(int N, int add = 0)
		{
			int[] Array = new int[N];
			for (int i = 0; i < N; i++) {
				Array[i] = Int() + add;
			}
			return Array;
		}

		public long[] ArrayLong(int N, long add = 0)
		{
			long[] Array = new long[N];
			for (int i = 0; i < N; i++) {
				Array[i] = Long() + add;
			}
			return Array;
		}

		public double[] ArrayDouble(int N, double add = 0)
		{
			double[] Array = new double[N];
			for (int i = 0; i < N; i++) {
				Array[i] = Double() + add;
			}
			return Array;
		}

		public void Save(string text)
		{
			if (string.IsNullOrWhiteSpace(filePath_)) {
				return;
			}

			File.WriteAllText(filePath_ + "_output.txt", text);
		}
	}
}

Measured memory_bytes: 36040