#include <bits/stdc++.h>

#include <algorithm>
#include <cassert>
#include <vector>

namespace atcoder {

// Implement (union by size) + (path compression)
// Reference:
// Zvi Galil and Giuseppe F. Italiano,
// Data structures and algorithms for disjoint set union problems
struct dsu {
  public:
    dsu() : _n(0) {}
    dsu(int n) : _n(n), parent_or_size(n, -1) {}

    int merge(int a, int b) {
        assert(0 <= a && a < _n);
        assert(0 <= b && b < _n);
        int x = leader(a), y = leader(b);
        if (x == y) return x;
        if (-parent_or_size[x] < -parent_or_size[y]) std::swap(x, y);
        parent_or_size[x] += parent_or_size[y];
        parent_or_size[y] = x;
        return x;
    }

    bool same(int a, int b) {
        assert(0 <= a && a < _n);
        assert(0 <= b && b < _n);
        return leader(a) == leader(b);
    }

    int leader(int a) {
        assert(0 <= a && a < _n);
        if (parent_or_size[a] < 0) return a;
        return parent_or_size[a] = leader(parent_or_size[a]);
    }

    int size(int a) {
        assert(0 <= a && a < _n);
        return -parent_or_size[leader(a)];
    }

    std::vector<std::vector<int>> groups() {
        std::vector<int> leader_buf(_n), group_size(_n);
        for (int i = 0; i < _n; i++) {
            leader_buf[i] = leader(i);
            group_size[leader_buf[i]]++;
        }
        std::vector<std::vector<int>> result(_n);
        for (int i = 0; i < _n; i++) {
            result[i].reserve(group_size[i]);
        }
        for (int i = 0; i < _n; i++) {
            result[leader_buf[i]].push_back(i);
        }
        result.erase(
            std::remove_if(result.begin(), result.end(),
                           [&](const std::vector<int>& v) { return v.empty(); }),
            result.end());
        return result;
    }

  private:
    int _n;
    // root node: -1 * component size
    // otherwise: parent
    std::vector<int> parent_or_size;
};

}  // namespace atcoder

typedef long long ll;
#define REP(i, n) for(int i = 0; i < n; i++)
#define REP2(i, a, b) for(int i = a;i <= b;i++)
#define REPR(i, a, b) for(int i = a; i >= b; i--)
#define FOR(i, m, n) for(int i = m; i < n; i++)
#define INF 2e9
#define MOD 1000000007
#define PI 3.14159265358979323846
#define vi vector<int>
#define vll vector<ll>
#define vi2 vector<vector<int>>
#define eb emplace_back
#define fi first
#define se second
#define ALL(v) v.begin(), v.end()
#define sz(x) int(x.size())
using namespace std;
using namespace atcoder;
using P = pair<ll,ll>;
const int dx[]{0, 1, 0, -1, -1, -1, 1, 1}, dy[]{1, 0, -1, 0, -1, 1, -1, 1};
#define INT(name) int name;cin >> name;
#define VEC(type,name,n) vector<type> name(n);REP(i,n) cin >> name[i];

template<class T> inline bool chmin(T& a, T b) {
  if (a > b) {
    a = b;
    return true;
  }
  return false;
}
template<class T> inline bool chmax(T& a, T b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}

int main()
{
  ll N,M;
  cin >> N >> M;
  dsu d(N+M);
  REP(i,N){
    ll K;
    cin >> K;
    REP(j,K){
      ll x;
      cin >> x;
      d.merge(i+M,x-1);
    }
  }

  int flag=0;
  REP(i,N){
    if(!d.same(M,i+M)){
      flag=1;
    }
  }

  if(flag==0){
    cout << "YES" << endl;
  }else{
    cout << "NO" << endl;
  }
}

Measured memory_bytes: 3952