#include <bits/stdc++.h>
using namespace std;
const int N = 1000001;
int n, k;
struct Edge {
  int to, next;
} edge[2 * N];
int head[N], cnt;
void add_edge(int u, int s) {
  cnt++;
  edge[cnt].to = s;
  edge[cnt].next = head[u];
  head[u] = cnt;
  return;
}
int rt = 1, in[N];
int dis[N];
int ans = 1;
int dfs(int u, int father) {
  if (in[u] == 1) return 0;
  vector<int> s;
  for (int i = head[u]; i; i = edge[i].next) {
    int v = edge[i].to;
    if (v == father) continue;
    s.push_back(dfs(v, u) + 1);
  }
  sort(s.begin(), s.end());
  for (int i = s.size() - 1; i > 0; i--)
    if (s[i] + s[i - 1] > k)
      ans++;
    else
      return s[i];
  return s[0];
}
int main() {
  scanf("%d%d", &n, &k);
  for (int i = 1; i < n; i++) {
    int x, y;
    scanf("%d%d", &x, &y);
    add_edge(x, y);
    add_edge(y, x);
    in[x]++, in[y]++;
  }
  while (in[rt] == 1) rt++;
  dfs(rt, 0);
  printf("%d", ans);
  return 0;
}
