#include <bits/stdc++.h>
using namespace std;
vector<long long> adj[1000001];
long long ass[1000001] = {0};
long long ans = 1, k;
long long dfs(long long pt, vector<long long> adj[], long long old) {
  vector<long long> z;
  for (auto i : adj[pt]) {
    if (i == old) continue;
    z.push_back(dfs(i, adj, pt));
  }
  sort(z.begin(), z.end());
  long long x = z.size(), ref;
  if (x != 0) ref = z[0];
  long long un = 0;
  for (long long i = 1; i < x; i++) {
    if (z[i] + z[i - 1] > k) {
      if (un == 0) ref = z[i - 1];
      ans++;
      un = 1;
    }
  }
  if (un == 0) {
    if (x == 0) {
      return 1;
    } else {
      return (z[x - 1] + 1);
    }
  } else {
    return ref + 1;
  }
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  long long n;
  cin >> n >> k;
  for (long long i = 0; i < n - 1; i++) {
    long long a, b;
    cin >> a >> b;
    adj[a].push_back(b);
    adj[b].push_back(a);
    ass[a]++;
    ass[b]++;
  }
  long long xe;
  for (long long i = 1; i <= n; i++) {
    if (ass[i] >= 2) {
      xe = i;
      break;
    }
  }
  dfs(xe, adj, -1);
  cout << ans << endl;
  return 0;
}
