#include <bits/stdc++.h>
using namespace std;
using Long = long long;
vector<vector<int>> G(100010);
int D[100010];
int dist[100010];
int P[100010];
int ep1 = -1, ep1lvl = -1, ep2 = -1, ep2lvl = -1;
void dfs(int u, int p, int lvl) {
  if (lvl > ep1lvl) {
    ep1lvl = lvl;
    ep1 = u;
  }
  for (auto v : G[u]) {
    if (v != p) dfs(v, u, lvl + 1);
  }
}
void dfs1(int u, int p, int lvl) {
  P[u] = p;
  if (lvl > ep2lvl) {
    ep2lvl = lvl;
    ep2 = u;
  }
  for (auto v : G[u]) {
    if (v != p) dfs1(v, u, lvl + 1);
  }
}
int md;
vector<int> path;
void getMid(int u) {
  while (P[u] != -1) {
    path.push_back(u);
    u = P[u];
  }
  path.push_back(u);
  reverse(path.begin(), path.end());
}
bool ok = true;
int n, k;
int main() {
  cin >> n >> k;
  memset(D, 0, sizeof(D));
  for (int i = 0; i < 100000; i++) P[i] = -1, dist[i] = 1 << 30;
  int first = 0;
  for (int i = 0; i < n - 1; i++) {
    int u, v;
    cin >> u >> v;
    u--, v--;
    if (!i) first = u;
    G[u].push_back(v);
    G[v].push_back(u);
    D[u]++, D[v]++;
  }
  dfs(first, -1, 1);
  dfs1(ep1, -1, 1);
  if (ep2lvl <= k) {
    puts("No");
    return 0;
  }
  getMid(ep2);
  md = path[k];
  queue<int> Q;
  Q.push(md);
  dist[md] = 0;
  while (!Q.empty()) {
    int u = Q.front();
    Q.pop();
    if (u == md) {
      if (D[u] < 3) ok = false;
    } else {
      if (dist[u] != k && (D[u] - 1) < 3) ok = false;
      if (dist[u] == k && D[u] > 1) ok = false;
    }
    for (int v : G[u]) {
      if (dist[v] == 1 << 30) {
        dist[v] = dist[u] + 1;
        Q.push(v);
      }
    }
  }
  (ok) ? puts("Yes") : puts("No");
  return 0;
}
