// clang-format off
#include <bits/stdc++.h>
#define int long long
#define main signed main()
// #define main int main()
#define loop(i, a, n) for (int i = (a); i < (n); i++)
#define rep(i, n) loop(i, 0, n)
#define all(v) (v).begin(), (v).end()
#define rall(v) (v).rbegin(), (v).rend()
#define prec(n) fixed << setprecision(n)
#define stlice(from, to) substr(from, (to) - (from) + 1)
#define pb push_back
#define mp make_pair
#define mt make_tuple
#define fi first
#define se second
using namespace std;
using pii = pair<int, int>;
using vi = vector<int>;
using vd = vector<double>;
using vc = vector<char>;
using vb = vector<bool>;
using vs = vector<string>;
using vpii = vector<pii>;
using vvi = vector<vi>;
using vvb = vector<vb>;
using vvpii = vector<vpii>;
template<typename A> using fn = function<A>;
constexpr int INF = sizeof(int) == sizeof(long long) ? 1000000000000000000LL : 1000000000;
constexpr int MOD = 1000000007;
constexpr double PI = acos(-1);
template<typename A, typename B> bool cmin(A &a, const B &b) { return a > b ? (a = b, true) : false; }
template<typename A, typename B> bool cmax(A &a, const B &b) { return a < b ? (a = b, true) : false; }
constexpr bool odd(const int &n) { return n & 1; }
constexpr bool even(const int &n) { return !odd(n); }
void solve();
main { solve(); return 0; }
// clang-format on
class UFT {
private:
vi data, rnk;
public:
UFT(const int &size)
: data(size), rnk(size) {
iota(all(data), 0);
}
int root(const int &x) {
return data[x] == x ? x : data[x] = root(data[x]);
}
bool same(const int &a, const int &b) {
return root(a) == root(b);
}
void unite(int a, int b) {
a = root(a), b = root(b);
if (a == b) return;
if (rnk[a] < rnk[b]) swap(a, b);
data[b] = a;
if (rnk[a] == rnk[b]) rnk[a]++;
}
};
void solve() {
int n, m;
cin >> n >> m;
UFT uf(n + m);
rep(i, n) {
int k;
cin >> k;
while (k--) {
int l;
cin >> l;
l--;
uf.unite(i, n + l);
}
}
bool b = true;
loop(i, 1, n) b &= uf.same(i - 1, i);
cout << (b ? "YES" : "NO") << endl;
}