#include <bits/stdc++.h>
using namespace std;
#define DEBUG_MODE
#define endl '\n'
#ifdef DEBUG_MODE
#define DEBUG(X) debug_func(X, #X)
#define DEBUG_ENDL endl
#define DEBUG_SEPARATOR_LINE cout<<"=================\n"
#else
#define DEBUG(X) 0
#define DEBUG_ENDL 0
#define DEBUG_SEPARATOR_LINE 0
#endif
#define ALL(V) (V).begin(), (V).end()
#define ALLR(V) (V).rbegin(), (V).rend()
#define DEBUG_ENDL_S(S) ((S).size() ? "\n" : "")
template <typename T> using V = vector<T>;
template <typename T> using VV = V<V<T>>;
template <typename T, typename U> using P = pair<T, U>;
using ll = int64_t;
using PLL = P<ll, ll>;
template <typename T> const T& var_min(const T &t) { return t; }
template <typename T> const T& var_max(const T &t) { return t; }
template <typename Head, typename... Tail> const Head& var_min(const Head &head, const Tail&... tail) { return min(head, var_min(tail...)); }
template <typename Head, typename... Tail> const Head& var_max(const Head &head, const Tail&... tail) { return max(head, var_max(tail...)); }
template <typename T, typename... Tail> void chmin(T &t, const Tail&... tail) { t = var_min(t, tail...); }
template <typename T, typename... Tail> void chmax(T &t, const Tail&... tail) { t = var_max(t, tail...); }
void debug_func_preffix(const string &s) { if(s.size()) cout << s << " = "; }
template <typename T>
void debug_func(const T &t, const string &s = "") {
    debug_func_preffix(s);
    cout << t << DEBUG_ENDL_S(s);
}
template <typename T, typename U>
void debug_func(const P<T, U> &p, const string &s = "") {
    debug_func_preffix(s);
    cout << "(";
    debug_func(p.first);
    cout << ", ";
    debug_func(p.second);
    cout << ")" << DEBUG_ENDL_S(s);
}
template <typename T>
void debug_func(const V<T> &v, const string &s = "") {
    for(ll i = 0; i < v.size(); i++) {
        string t = s + "[" + to_string(i) + "]";
        debug_func(v[i], t);
    }
}

class UnionFind{
    using vec = vector<ll>;
    public:
        vec rank;
        vec parent;

        UnionFind(ll N){
            rank = vec(N, 0);
            parent = vec(N);
            iota(parent.begin(), parent.end(), 0ll);
        }

        ~UnionFind(){
        }

        ll find(ll child){
            return (child == parent[child] ? child : parent[child] = find(parent[child]));
        }

        void unit(ll x, ll y){
            ll px = find(x);
            ll py = find(y);
            if(px == py){
                return;
            }
            if(rank[px] < rank[py]){
                swap(px, py);
            }
            parent[py] = px;
            rank[px] += (rank[px] == rank[py]);
        }

        bool same(ll x, ll y){
            return (find(x) == find(y));
        }

};

int main() {
    ll N, M;
    cin >> N >> M;
    UnionFind UF(N);
    VV<ll> lv(M);
    for(ll i = 0; i < N; i++) {
        ll K;
        cin >> K;
        for(ll j = 0; j < K; j++) {
            ll L;
            cin >> L;
            lv[L - 1].push_back(i);
        }
    }
    for(const auto &v : lv) for(ll i = 0; i < (ll)v.size() - 1; i++) UF.unit(v[i], v[i + 1]);
    V<ll> pv;
    for(ll i = 0; i < N; i++) pv.push_back(UF.find(i));
    sort(ALL(pv));
    auto ite = unique(ALL(pv));
    pv.erase(ite, pv.end());
    cout << (pv.size() == 1 ? "YES" : "NO") << endl;
    return 0;
}


Measured memory_bytes: 6516