#include <bits/stdc++.h>
using namespace std;
int n, k;
vector<int> adj[(int)1e5 + 7];
int vis[(int)1e5 + 7];
int deg[(int)1e5 + 7];
int cnt[(int)1e5 + 7];
int main() {
  ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0);
  ;
  scanf("%d %d", &n, &k);
  for (int i = 1; i <= n - 1; i++) {
    int u, v;
    scanf("%d %d", &u, &v);
    adj[u].push_back(v);
    adj[v].push_back(u);
    deg[v]++;
    deg[u]++;
  }
  int lvl = 0;
  queue<int> q;
  for (int i = 1; i <= n; i++)
    if (deg[i] == 1) q.push(i);
  while (q.size()) {
    set<int> kroots;
    int sz = q.size();
    while (sz--) {
      int root = q.front();
      q.pop();
      vis[root] = 1;
      for (auto neighbour : adj[root]) {
        if (vis[neighbour]) {
          continue;
        }
        deg[neighbour]--;
        cnt[neighbour]++;
        kroots.insert(neighbour);
      }
    }
    for (auto val : kroots) {
      if (vis[val] || deg[val] > 1 || cnt[val] < 3) {
        puts("No");
        return 0;
      }
      q.push(val);
    }
    if (kroots.size())
      lvl++;
    else
      break;
  }
  if (lvl == k)
    puts("Yes");
  else
    puts("No");
  return 0;
}
