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