/*
                              _,add8ba,
                            ,d888888888b,
                           d8888888888888b                        _,ad8ba,_
                          d888888888888888)                     ,d888888888b,
                          I8888888888888888 _________          ,8888888888888b
                __________`Y88888888888888P"""""""""""baaa,__ ,888888888888888,
            ,adP"""""""""""9888888888P""^                 ^""Y8888888888888888I
         ,a8"^           ,d888P"888P^                           ^"Y8888888888P'
       ,a8^            ,d8888'                                     ^Y8888888P'
      a88'           ,d8888P'                                        I88P"^
    ,d88'           d88888P'                                          "b,
   ,d88'           d888888'                                            `b,
  ,d88'           d888888I                                              `b,
  d88I           ,8888888'            ___                                `b,
 ,888'           d8888888          ,d88888b,              ____            `b,
 d888           ,8888888I         d88888888b,           ,d8888b,           `b
,8888           I8888888I        d8888888888I          ,88888888b           8,
I8888           88888888b       d88888888888'          8888888888b          8I
d8886           888888888       Y888888888P'           Y8888888888,        ,8b
88888b          I88888888b      `Y8888888^             `Y888888888I        d88,
Y88888b         `888888888b,      `""""^                `Y8888888P'       d888I
`888888b         88888888888b,                           `Y8888P^        d88888
 Y888888b       ,8888888888888ba,_          _______        `""^        ,d888888
 I8888888b,    ,888888888888888888ba,_     d88888888b               ,ad8888888I
 `888888888b,  I8888888888888888888888b,    ^"Y888P"^      ____.,ad88888888888I
  88888888888b,`888888888888888888888888b,     ""      ad888888888888888888888'
  8888888888888698888888888888888888888888b_,ad88ba,_,d88888888888888888888888
  88888888888888888888888888888888888888888b,`"""^ d8888888888888888888888888I
  8888888888888888888888888888888888888888888baaad888888888888888888888888888'
  Y8888888888888888888888888888888888888888888888888888888888888888888888888P
  I888888888888888888888888888888888888888888888P^  ^Y8888888888888888888888'
  `Y88888888888888888P88888888888888888888888888'     ^88888888888888888888I
   `Y8888888888888888 `8888888888888888888888888       8888888888888888888P'
    `Y888888888888888  `888888888888888888888888,     ,888888888888888888P'
     `Y88888888888888b  `88888888888888888888888I     I888888888888888888'
       "Y8888888888888b  `8888888888888888888888I     I88888888888888888'
         "Y88888888888P   `888888888888888888888b     d8888888888888888'
            ^""""""""^     `Y88888888888888888888,    888888888888888P'
                             "8888888888888888888b,   Y888888888888P^
                              `Y888888888888888888b   `Y8888888P"^
                                "Y8888888888888888P     `""""^
                                  `"YY88888888888P'
                                       ^""""""""'
*/
#include <bits/stdc++.h>

#define pb push_back
#define pf push_front
#define in insert
#define F first
#define S second
#define sz(a) int (a.size ())
#define mp make_pair
#define GGWP return 0
#define all(a) (a).begin(), (a).end()
#define pii pair<int,int>
#define graph vector <vector <int> >
#define fname ""

typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;

using namespace std;
const int inf = int (1e9);
const double eps = 0.0000000001, pi = 3.14159265358979323;
const int maxn = int (1e5);
graph g;
bool u[maxn * 5];
int n, m;

inline void dfs (int v) {
	u[v] = 1;

	for (auto to : g[v]) {
		if (!u[to]) {
			dfs (to);
		}
	}
}

inline bool check () {
	for (int i=1; i<=n; ++i)
		if (!u[i])
			return false;
	return true; 
}

int main () {
	ios::sync_with_stdio(0);
	cin.tie(0);
                                               

	cin >> n >> m;
	g.resize (maxn * 2 + 10);

	for (int i=1; i<=n; ++i) {
		int k;
		cin >> k;
		for (int j=1; j<=k; ++j) {
			int l;
			cin >> l;
			g[i].pb (l + maxn);
			g[l + maxn].pb (i);
		}
	}

	dfs (1); 

	if (check ()) 
		cout << "YES";
	else
		cout << "NO";

	GGWP;
}


Measured memory_bytes: 8704