#include <bits/stdc++.h>
using namespace std;
int n, k, x, y, ind = 0, ans = 0;
vector<int> v[1000010];
int dfs(int s, int c) {
  vector<int> sz;
  if (v[s].size() == 1) return 0;
  for (auto it : v[s]) {
    if (it != c) sz.push_back(1 + dfs(it, s));
  }
  sort(sz.begin(), sz.end());
  while (sz.size() > 1) {
    if (sz[sz.size() - 1] + sz[sz.size() - 2] > k) {
      ans++;
      sz.pop_back();
    } else
      break;
  }
  return sz[sz.size() - 1];
}
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  cin >> n >> k;
  for (int i = 0; i < n - 1; i++) {
    cin >> x >> y;
    v[x].push_back(y);
    v[y].push_back(x);
  }
  for (int i = 1; i <= n; i++) {
    if (v[i].size() > 1) {
      ind = i;
      break;
    }
  }
  dfs(ind, -1);
  cout << ans + 1;
  return 0;
}
