#include <bits/stdc++.h>
using namespace std;
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int n, k;
  cin >> n >> k;
  vector<vector<int>> g(n);
  for (int i = 0; i < n - 1; ++i) {
    int x, y;
    cin >> x >> y;
    --x;
    --y;
    g[x].push_back(y);
    g[y].push_back(x);
  }
  int ans = 1;
  function<int(int, int)> dfs = [&](int v, int pv) {
    if ((int)g[v].size() == 1) {
      return 0;
    }
    vector<int> d;
    for (int to : g[v]) {
      if (to == pv) {
        continue;
      }
      d.push_back(1 + dfs(to, v));
    }
    sort(d.begin(), d.end());
    while ((int)d.size() >= 2) {
      if (d.back() + d[(int)d.size() - 2] <= k) {
        break;
      }
      ++ans;
      d.pop_back();
    }
    return d.back();
  };
  for (int i = 0; i < n; ++i) {
    if ((int)g[i].size() > 1) {
      dfs(i, -1);
      break;
    }
  }
  cout << ans << '\n';
  return 0;
}
