//
//
//  Codeforces: ganariya
//  AtCoder: ganariya2525
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//include
//------------------------------------------
#include <vector>
#include <list>
#include <map>
#include <unordered_map>
#include <climits>
#include <set>
#include <unordered_set>
#include <deque>
#include <stack>
#include <bitset>
#include <algorithm>
#include <functional>
#include <numeric>
#include <utility>
#include <sstream>
#include <iostream>
#include <iomanip>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <cctype>
#include <string>
#include <cstring>
#include <ctime>
#include <queue>
#include <random>
#include <complex>
#include <regex>
#include <locale>
#include <random>

using namespace std;

#define SHOW_VECTOR(v) {std::cerr << #v << "\t:";for(const auto& xxx : v){std::cerr << xxx << " ";}std::cerr << "\n";}
#define SHOW_MAP(v){std::cerr << #v << endl; for(const auto& xxx: v){std::cerr << xxx.first << " " << xxx.second << "\n";}}

using LL = long long;

//~~~~~~~~~~~~~~~~~~~~~_(＾～＾ ｣ ∠)_~~~~~~~~~~~~~~~~~~~~~

struct UnionFind {
    vector<int> par, sizes;

    UnionFind(int n)
            : par(n, 1), sizes(n, 1) {
        for (int i = 0; i < n; i++) par[i] = i;
    }

    int find(int x) {
        return x == par[x] ? x : par[x] = find(par[x]);
    }

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

    void unite(int x, int y) {
        x = find(x);
        y = find(y);
        if (x == y) return;
        if (sizes[x] < sizes[y]) swap(x, y);
        sizes[x] += sizes[y];
        par[y] = x;
    }

    bool all_same() {
        bool good = true;
        for (int i = 0; i < par.size(); i++) if (find(0) != find(i)) good = false;
        return good;
    }

};

int main() {

    int n, m;
    cin >> n >> m;

    UnionFind UF(n);
    vector<vector<int>> lang(m, vector<int>());


    for (int i = 0; i < n; i++) {
        int k;
        cin >> k;
        for (int j = 0; j < k; j++) {
            int l;
            cin >> l;
            l--;
            lang[l].push_back(i);
        }
    }

    for (int i = 0; i < m; i++) {
        for (int j = 1; j < lang[i].size(); j++) {
            UF.unite(lang[i][0], lang[i][j]);
        }
    }

    if (UF.all_same()) cout << "YES";
    else cout << "NO";

    return 0;
}















































Measured memory_bytes: 4608