#include <cstdio>
#include <cstdlib>
#include <algorithm>
#include <vector>
#include <string>
#include <cstring>
#include <queue>
#include <set>
#include <unordered_set>
#include <unordered_map>
#include <map>
#include <numeric>
#include <functional>
#include <cmath>
#include <cassert>
#include <string>
#include <iostream>

using namespace std;
typedef long long ll;
typedef pair<int, int> P;
typedef pair<ll, ll> PL;
const ll MOD = 1000000007;
const int mod = 1000000007;
ll INF = 1LL << 60;

template <typename T>
istream &operator>>(istream &is, vector<T> &vec)
{
   for (auto &v : vec)
      is >> v;
   return is;
}
template <typename T>
ostream &operator<<(ostream &os, const vector<T> &vec)
{
   os << "[";
   for (auto v : vec)
      os << v << ",";
   os << "]";
   return os;
}
template <typename T>
ostream &operator<<(ostream &os, const deque<T> &vec)
{
   os << "deq[";
   for (auto v : vec)
      os << v << ",";
   os << "]";
   return os;
}
template <typename T>
ostream &operator<<(ostream &os, const set<T> &vec)
{
   os << "{";
   for (auto v : vec)
      os << v << ",";
   os << "}";
   return os;
}
template <typename T>
ostream &operator<<(ostream &os, const unordered_set<T> &vec)
{
   os << "{";
   for (auto v : vec)
      os << v << ",";
   os << "}";
   return os;
}
template <typename T>
ostream &operator<<(ostream &os, const multiset<T> &vec)
{
   os << "{";
   for (auto v : vec)
      os << v << ",";
   os << "}";
   return os;
}
template <typename T>
ostream &operator<<(ostream &os, const unordered_multiset<T> &vec)
{
   os << "{";
   for (auto v : vec)
      os << v << ",";
   os << "}";
   return os;
}
template <typename T1, typename T2>
ostream &operator<<(ostream &os, const pair<T1, T2> &pa)
{
   os << "(" << pa.first << "," << pa.second << ")";
   return os;
}
template <typename TK, typename TV>
ostream &operator<<(ostream &os, const map<TK, TV> &mp)
{
   os << "{";
   for (auto v : mp)
      os << v.first << "=>" << v.second << ",";
   os << "}";
   return os;
}
template <typename TK, typename TV>
ostream &operator<<(ostream &os, const unordered_map<TK, TV> &mp)
{
   os << "{";
   for (auto v : mp)
      os << v.first << "=>" << v.second << ",";
   os << "}";
   return os;
};
#define dbg(x) cerr << #x << " = " << (x) << " (L" << __LINE__ << ") " << __FILE__ << endl;
template <typename A, size_t N, typename T>
void Fill(A (&array)[N], const T &val)
{
   fill((T *)array, (T *)(array + N), val);
}

struct UnionFind {
    vector<int> par;
    
    UnionFind(int n) : par(n, -1) { }
    void init(int n) { par.assign(n, -1); }
    
    int root(int x) {
        if (par[x] < 0) return x;
        else return par[x] = root(par[x]);
    }
    
    bool issame(int x, int y) {
        return root(x) == root(y);
    }
    
    bool merge(int x, int y) {
        x = root(x); y = root(y);
        if (x == y) return false;
        if (par[x] > par[y]) swap(x, y); // merge technique
        par[x] += par[y];
        par[y] = x;
        return true;
    }
    
    int size(int x) {
        return -par[root(x)];
    }
};



ll a[202020];
int solve()
{
   ll n,m;
   cin >> n >> m;
   UnionFind uf(m);
   map<int, bool> ma;
   for(int i=0; i < n; i++){
      ll k,t;
      cin >> k;

      for(int j=0; j < k; j++){
         int a;
         cin >> a;
         a--;
         ma[a] = true;
         if(j != 0){
            uf.merge(a, t);
         }
         t = a;
      }
   }

   set<int> s;
   for(int i=0; i < m; i++){
      if(ma[i])s.insert(uf.root(i));
   }
   //dbg(s.size());
   //cout << uf.par << endl;

   if (s.size() == 1)
   {
      cout << "YES" << endl;
   }else{
      cout << "NO" << endl;
   }
   



   return 0;
}

int main()
{
   //cout.precision(10)
   ios::sync_with_stdio(false);
   cin.tie(0);

   solve();
}

Measured memory_bytes: 5376