#include <bits/stdc++.h>
using namespace std;
const int maxn = 1e6 + 50;
vector<int> v[maxn];
int ans;
int n, k;
int dfs(int x, int p) {
  if (v[x].size() == 1) return 0;
  vector<int> c;
  for (int i = 0; i < v[x].size(); i++) {
    if (v[x][i] == p) continue;
    c.push_back(dfs(v[x][i], x) + 1);
  }
  sort(c.begin(), c.end());
  while (c.size() >= 2) {
    if (c[c.size() - 1] + c[c.size() - 2] <= k) break;
    ++ans;
    c.resize(c.size() - 1);
  }
  return c[c.size() - 1];
}
int main() {
  cin >> n >> k;
  for (int i = 1; i < n; i++) {
    int x, y;
    scanf("%d%d", &x, &y);
    v[x].push_back(y);
    v[y].push_back(x);
  }
  for (int i = 1; i <= n; i++) {
    if (v[i].size() > 1) {
      dfs(i, 0);
      cout << ans + 1;
      return 0;
    }
  }
  return 0;
}
