#include <bits/stdc++.h>
using namespace std;
int read() {
  char ch = getchar();
  int x = 0;
  while (ch > '9' || ch < '0') ch = getchar();
  while (ch >= '0' && ch <= '9') x = x * 10 + ch - '0', ch = getchar();
  return x;
}
int n, num, ans, k;
int head[1000010], in[1000010];
struct point {
  int to, next;
} e[1000010 << 1];
void add(int from, int to) {
  e[++num].next = head[from];
  e[num].to = to;
  head[from] = num;
}
int dfs(int x, int fa) {
  if (in[x] == 1) return 0;
  priority_queue<int> q;
  for (int i = head[x]; i; i = e[i].next) {
    int to = e[i].to;
    if (to == fa) continue;
    q.push(dfs(to, x) + 1);
  }
  int maxn = q.top();
  q.pop();
  while (!q.empty()) {
    if (q.top() + maxn <= k) return maxn;
    ans++;
    maxn = q.top();
    q.pop();
  }
  return maxn;
}
int main() {
  n = read();
  k = read();
  for (int i = 1; i < n; i++) {
    int a = read(), b = read();
    add(a, b);
    add(b, a);
    in[a]++;
    in[b]++;
  }
  for (int i = 1; i <= n; i++)
    if (in[i] != 1) {
      dfs(i, 0);
      break;
    }
  printf("%d", ans + 1);
  return 0;
}
