#include <bits/stdc++.h>
using namespace std;
vector<int> FindCenter(vector<vector<int>>& G) {
  int c = 1;
  vector<int> P;
  queue<int> q;
  for (int j = 0; j < 2; j++) {
    P.assign(G.size(), -1);
    P[c] = c;
    q.push(c);
    while (!q.empty()) {
      c = q.front();
      q.pop();
      for (auto& u : G[c])
        if (P[u] == -1) q.push(u), P[u] = c;
    }
  }
  vector<int> diameter = {c};
  while (P[c] != c) c = P[c], diameter.push_back(c);
  if (diameter.size() % 2 == 1) return {diameter[diameter.size() / 2]};
  return {diameter[diameter.size() / 2 - 1], diameter[diameter.size() / 2]};
}
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  int n, k;
  cin >> n >> k;
  vector<vector<int>> G(n + 1);
  for (int i = 1; i < n; i++) {
    int u, v;
    cin >> u >> v;
    G[u].push_back(v);
    G[v].push_back(u);
  }
  int center = FindCenter(G)[0];
  queue<int> q;
  vector<int> D(n + 1, INT_MAX);
  D[center] = 0;
  q.push(center);
  if (G[center].size() < 3) return cout << "No", 0;
  while (!q.empty()) {
    int c = q.front();
    q.pop();
    if (G[c].size() == 1 && D[c] != k) return cout << "No", 0;
    if (G[c].size() < 4 && D[c] < k && c != center) return cout << "No", 0;
    for (auto& u : G[c])
      if (D[u] == INT_MAX) D[u] = D[c] + 1, q.push(u);
  }
  cout << "Yes\n";
}
