#include <bits/stdc++.h>
using namespace std;
const int MM = 120000;
vector<int> G[MM], T[MM];
int P[MM], L[MM];
void dfs(int u, int par) {
  P[u] = par;
  if (par != -1) L[u] = L[par] + 1;
  for (auto v : G[u]) {
    if (v != par) {
      dfs(v, u);
    }
  }
}
int N, K;
bool rip = 0;
void dfs2(int u, int par, int lev) {
  int kek = 0;
  for (auto v : G[u]) {
    if (v != par) {
      kek++;
      dfs2(v, u, lev + 1);
    }
  }
  if (kek < 3 && kek != 0) {
    rip = 1;
  }
  if (kek == 0 && lev != K) {
    rip = 1;
  }
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  cin >> N >> K;
  for (int i = 0; i < N - 1; i++) {
    int u, v;
    cin >> u >> v;
    G[u - 1].push_back(v - 1);
    G[v - 1].push_back(u - 1);
  }
  dfs(0, -1);
  int mx = 0;
  int el = -1;
  for (int i = 0; i < N; i++) {
    mx = max(mx, L[i]);
    if (mx == L[i]) {
      el = i;
    }
  }
  if (mx >= K) {
    mx = K;
    while (mx--) el = P[el];
    int rt = el;
    dfs2(rt, -1, 0);
    if (rip) {
      cout << "No";
    } else {
      cout << "Yes";
    }
  } else {
    cout << "No";
    return 0;
  }
  return 0;
}
