#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  int n, k;
  cin >> n >> k;
  vector<int> adj[n];
  int deg[n];
  for (int i = 0; i < n; i++) {
    deg[i] = 0;
  }
  for (int i = 1; i < n; i++) {
    int a, b;
    cin >> a >> b;
    a--;
    b--;
    adj[a].push_back(b);
    adj[b].push_back(a);
    deg[a]++;
    deg[b]++;
  }
  vector<int> li;
  for (int i = 0; i < n; i++) {
    if (deg[i] == 1) {
      li.push_back(i);
    }
  }
  for (int i = 0; i < li.size(); i++) {
    int now = li[i];
    for (int j = 0; j < adj[now].size(); j++) {
      int to = adj[now][j];
      deg[to]--;
      if (deg[to] == 1) {
        li.push_back(to);
      }
    }
  }
  if (li.size() != n) {
    cout << "No" << endl;
    return 0;
  }
  bool v[n];
  int deep[n];
  for (int i = 0; i < n; i++) {
    v[i] = false;
    deep[i] = -1;
  }
  v[li[n - 1]] = true;
  deep[li[n - 1]] = 0;
  bool ok = true;
  for (int i = n - 1; i >= 0; i--) {
    int now = li[i];
    if (!v[now] || deep[now] > k) {
      ok = false;
      break;
    }
    int red = adj[now].size();
    if (i < n - 1) {
      red--;
    }
    if (red < 3 && deep[now] != k) {
      ok = false;
      break;
    }
    for (int j = 0; j < adj[now].size(); j++) {
      int to = adj[now][j];
      if (!v[to]) {
        v[to] = true;
        deep[to] = deep[now] + 1;
      }
    }
  }
  cout << (ok ? "Yes" : "No") << endl;
}
