#include <bits/stdc++.h>
using namespace std;
inline int read() {
  int x = 0, f = 1;
  char ch = getchar();
  while (ch < '0' || ch > '9') {
    if (ch == '-') f = -1;
    ch = getchar();
  }
  while (ch >= '0' && ch <= '9') {
    x = 10 * x + ch - '0';
    ch = getchar();
  }
  return x * f;
}
inline long long readll() {
  long long x = 0, f = 1;
  char ch = getchar();
  while (ch < '0' || ch > '9') {
    if (ch == '-') f = -1;
    ch = getchar();
  }
  while (ch >= '0' && ch <= '9') {
    x = 10 * x + ch - '0';
    ch = getchar();
  }
  return x * f;
}
long long gcd(long long x, long long y) { return y ? gcd(y, x % y) : x; }
long long power(long x, long y) {
  long long t = 1;
  for (; y; y >>= 1, x = x * x % (1000000007))
    if (y & 1) t = t * x % (1000000007);
  return t;
}
int n, k, ans;
vector<int> G[(1000000 + 5)];
int dfs(int x, int fa = -1) {
  vector<int> t;
  for (int i = 0; i < G[x].size(); i++) {
    int y = G[x][i];
    if (y == fa) continue;
    t.push_back(dfs(y, x) + 1);
  }
  if (t.empty()) return 0;
  sort(t.begin(), t.end());
  while (1) {
    int m = t.size();
    if (m == 1 || t[m - 1] + t[m - 2] <= k)
      break;
    else
      ans++, t.pop_back();
  }
  return t.back();
}
int main() {
  n = read();
  k = read();
  for (int i = 1; i <= n - 1; i++) {
    int x = read(), y = read();
    G[x].push_back(y);
    G[y].push_back(x);
  }
  for (int i = 1; i <= n; i++)
    if (G[i].size() > 1) {
      dfs(i);
      break;
    }
  cout << ans + 1 << endl;
  return 0;
}
