#include <bits/stdc++.h>
using namespace std;
template <class X, class Y>
void amin(X& x, const Y& y) {
  if (x > y) x = y;
}
template <class X, class Y>
void amax(X& x, const Y& y) {
  if (x < y) x = y;
}
const int INF = 1e9 + 10;
const long long INFL = (long long)1e18 + 10;
const int MAX = 1e5 + 10;
int n, k;
vector<int> es[MAX];
int par[MAX], h[MAX];
void yes() {
  cout << "Yes";
  exit(0);
}
void no() {
  cout << "No";
  exit(0);
}
void visit(int u) {
  for (auto v : es[u])
    if (v != par[u]) {
      par[v] = u;
      h[v] = h[u] + 1;
      visit(v);
    }
}
bool check(int u, int p, int k) {
  if ((int((es[u]).size())) == 1) return k == 0;
  if (k == 0) return false;
  if (p != 0 && (int((es[u]).size())) <= 3) return false;
  for (auto v : es[u])
    if (v != p) {
      if (!check(v, u, k - 1)) return false;
    }
  return true;
}
void process() {
  cin >> n >> k;
  for (int i = 1; i < n; i++) {
    int u, v;
    cin >> u >> v;
    es[u].push_back(v);
    es[v].push_back(u);
  }
  for (int i = 1; i <= n; i++)
    if ((int((es[i]).size())) == 2) no();
  int root = 0;
  for (int i = 1; i <= n; i++)
    if ((int((es[i]).size())) == 1) {
      visit(i);
      int mv = i;
      for (int j = 1; j <= n; j++)
        if (h[j] > h[mv]) mv = j;
      if (h[mv] != 2 * k) no();
      while (h[mv] != k) mv = par[mv];
      root = mv;
      break;
    }
  if (root == 0) no();
  if (check(root, 0, k))
    yes();
  else
    no();
}
int main() {
  ios_base::sync_with_stdio(false);
  process();
}
