#include <bits/stdc++.h>
using namespace std;

typedef ostringstream OSS; typedef istringstream ISS;
typedef long long LL;
typedef pair<int, int> PII;  typedef pair<LL, LL> PLL;
typedef vector<int>    VI;   typedef vector<VI>   VVI;   typedef vector<VVI>   VVVI;
typedef vector<LL>     VLL;  typedef vector<VLL>  VVLL;  typedef vector<VVLL>  VVVLL;
typedef vector<double> VD;   typedef vector<VD>   VVD;   typedef vector<VVD>   VVVD;
typedef vector<string> VS;   typedef vector<VS>   VVS;   typedef vector<VVS>   VVVS;
typedef vector<bool>   VB;   typedef vector<VB>   VVB;   typedef vector<VVB>   VVVB;
typedef vector<PII>    VPII; typedef vector<VPII> VVPII; typedef vector<VVPII> VVVPII;
typedef vector<PLL>    VPLL; typedef vector<VPLL> VVPLL; typedef vector<VVPLL> VVVPLL;

typedef unsigned int  UI;
typedef vector<UI>    VUI;
typedef vector<VUI>   VVUI;

#define fst first
#define snd second
// #define Y first
// #define X second
#define MP make_pair
#define PB push_back
#define EB emplace_back 
#define ALL(x)  (x).begin(),(x).end()
#define RALL(x) (x).rbegin(),(x).rend()
#define RANGEBOX(x,y,maxX,maxY) (0 <= (x) && 0 <= (y) && (x) < (maxX) && (y) < (maxY))
#define RANGE(x, l, r) ((l) <= (x) && (x) <= (r))
#define rep(i, N)  for (int i = 0; i < (int)(N); i++)
#define rrep(i, N) for (int i = N - 1; i >= 0; i--)
#define REP(i, init, N)  for (int i = (init); i < (int)(N); i++)
#define RREP(i, N, last) for (int i = (init - 1); i >= last; i--)
#define MAXUD(orig, target) orig = max(orig, target)
#define MINUD(orig, target) orig = min(orig, target)
#define DUMP(x) cerr << #x << " = " << (x) << endl

template < typename T > inline T fromString(const string &s) { T res; ISS iss(s); iss >> res; return res; };
template < typename T > inline string toString(const T &a)   { OSS oss; oss << a; return oss.str(); };

template<typename T=int> inline void dump(vector<T> vs, bool ent=false) { rep(i, vs.size()) cout << vs[i] << (i+1==vs.size() ? '\n' : ' '); if (ent) cout << endl; }
template<typename T = int> inline void dump(vector<vector<T>> vs, bool ent=false) { rep(i, vs.size()) dump<T>(vs[i]); if (ent) cout << endl; }

const int    INF  = 0x3f3f3f3f;
const LL     INFL = 0x3f3f3f3f3f3f3f3fLL;
const double DINF = 0x3f3f3f3f;
const int    DX[] = {1,  0, -1, 0};
const int    DY[] = {0, -1,  0, 1};
const double EPS  = 1e-12;
// const double PI   = acos(-1.0);

template<typename T = int> inline T in() { T x; cin >> x; return x; }
template<typename T = int> inline vector<T> in(int n) { vector<T> xs(n); rep(i, n) cin >> xs[i]; return xs; }
template<typename T = int> inline vector<vector<T>> in(int n, int m) { vector<vector<T>> xs(n, vector<T>(m)); rep(i, n) rep(j, m) cin >> xs[i][j]; return xs; }

/***** Union-Find *****/

class UnionFind {
public:
    int n;
    VI roots, ranks, cnts;
    UnionFind(int n_) : n(n_), roots(n_), ranks(n_), cnts(n_, 1) {
        iota(ALL(roots), 0);
    }

    int find(int v) {
        return roots[v] = roots[v] == v ? v : find(roots[v]);
    }

    bool same(int a, int b) {
        return find(a) == find(b);
    }

    int count(int v) {
        return cnts[find(v)];
    }

    void unite(int a, int b) {
        a = find(a);
        b = find(b);
        if (a == b) return;

        if (ranks[a] < ranks[b]) {
            roots[a] = b;
            cnts[b] += cnts[a];
        } else {
            roots[b] = a;
            cnts[a] += cnts[b];
            if (ranks[a] == ranks[b]) ranks[a]++;
        }
    }
};

/***** /Union-Find *****/


int main(void) {
    int n, m;
    cin >> n >> m;

    VVI xs(m);
    rep(i, n) {
        int k = in();
        rep(j, k) {
            int x = in();
            --x;
            xs[x].PB(i);
        }
    }

    auto uf = UnionFind(n);
    rep(i, m) {
        REP(j, 1, xs[i].size()) {
            uf.unite(xs[i][0], xs[i][j]);
        }
    }

    cout << (uf.count(0) == n ? "YES" : "NO") << endl;

    return 0;
}



Measured memory_bytes: 4608