#include <bits/stdc++.h>
using namespace std;
int n, k;
vector<int> v[1000005];
int h[1000005];
int d[1000005], m[1000005];
void pre(int a, int p) {
  h[a] = h[p] + 1;
  for (auto i : v[a]) {
    if (i != p) pre(i, a);
  }
}
void dfs(int a, int p) {
  for (auto i : v[a]) {
    if (i == p) continue;
    dfs(i, a);
    d[a] += d[i];
  }
  if (v[a].size() == 1) {
    d[a] = 0;
    m[a] = h[a];
    return;
  }
  multiset<int> S;
  for (auto i : v[a]) {
    if (i == p) continue;
    S.insert(m[i]);
  }
  while (S.size() > 1) {
    auto it = S.begin();
    auto it2 = ++it;
    it--;
    if ((*it) + (*it2) <= k + 2 * h[a]) {
      S.erase(it);
    } else
      break;
  }
  m[a] = *S.begin();
  d[a] += S.size();
  d[a]--;
}
int main() {
  ios::sync_with_stdio(0);
  cin.tie(NULL);
  cin >> n >> k;
  for (int i = 1; i <= n - 1; i++) {
    int x, y;
    cin >> x >> y;
    v[x].push_back(y);
    v[y].push_back(x);
  }
  int root = 0;
  for (int i = 1; i <= n; i++) {
    if (v[i].size() > 1) {
      root = i;
      break;
    }
  }
  pre(root, 0);
  dfs(root, 0);
  cout << d[root] + 1 << endl;
  return 0;
}
