/**
 * code generated by JHelper
 * More info: https://github.com/AlexeyDmitriev/JHelper
 * @author champon
 */

#include <iostream>
#include <fstream>

#include <bits/stdc++.h>
#define se cout << "test ok" << endl;
#define sp << " " <<
#define enl "\n";
using namespace std;
using ll=long long;
using ld=long double;
ll mod = ll(1e9)+7;
ll inf = ll(1e18);
void bl(bool b, ostream& out=cout){ out << (b ? "Yes" : "No") << endl; }
void bl2(bool b, ostream& out=cout){ out << (b ? "YES" : "NO") << endl; }
template<typename T> inline bool chmax(T &a, T b){ if(a<b){a=b; return true;} return false; }
template<typename T> inline bool chmin(T &a, T b){ if(a>b){a=b; return true;} return false; }
template<typename A, size_t N, typename T> void Fill(A (&array)[N], const T &val){ fill((T*)array, (T*)(array+N), val); }
int dx[] = {1, 0, -1, 0, 1, -1, 1, -1};
int dy[] = {0, 1, 0, -1, 1, -1, -1, 1};

#ifndef INCLUDE_DEBUG_HPP
#define INCLUDE_DEBUG_HPP

#include <iostream>
#include <vector>
#include <map>
using namespace std;

namespace dbg {
    using ll = long long;

    class Debug {
    public:
        Debug(){}
        template<typename T>
        void vd(vector<T> vec);
        template<typename T>
        void vd2(vector<vector<T>> vec);
        template<typename T>
        void ad(T *arr, ll n);
        template<typename T, size_t N>
        void ad2(T (&arr)[N], ll n);
        template<typename T>
        void md(T mp);
    };

    template<typename T>
    void Debug::vd(vector<T> vec) {
        for (auto vv : vec) cout << vv << " ";
        cout << endl;
    }

    template<typename T>
    void Debug::vd2(vector<vector<T>> vec) {
        for (auto vv : vec) for (auto vvv : vv) cout << vvv << " ";
        cout << endl;
    }

    template<typename T>
    void Debug::ad(T *arr, ll n) {
        for (int i = 0; i <= n; i++) cout << arr[i] << " ";
        cout << endl;
    }

    template<typename T, size_t N>
    void Debug::ad2(T (&arr)[N], ll n) {
        for (int i = 0; i <= N; i++) for (int j = 0; j <= n; j++) cout << arr[i][j] << " ";
        cout << endl;
    }

    template<typename T>
    void Debug::md(T mp) {
        cout << "key : value" << endl;
        for (auto const &m : mp) cout << m.first << " : " << m.second << endl;
        cout << endl;
    }

}

#endif //INCLUDE_DEBUG_HPP

using dbg::Debug;
Debug debug;

#ifndef DEFINE_UNIONFIND_HPP
#define DEFINE_UNIONFIND_HPP


#include <numeric>

using namespace std;

namespace unionfind {

    using ll = long long;

    class UnionFind {
    public:
        ll n;
        vector<ll> par;
        vector<ll> rank;
        vector<ll> size;

        UnionFind(int n);
        ll find(ll x);
        void unite(ll x, ll y);
        bool same(ll x, ll y);
        ll getsize(ll x);
        int rootCount();
    };

    UnionFind::UnionFind(int n):n(n), par(n, 0), rank(n, 0), size(n, 1) {
        iota(par.begin(), par.end(), 0);
    }

    ll UnionFind::find(ll x) {
        if (par[x] == x) return x;
        else return par[x] = find(par[x]);
    }

    void UnionFind::unite(ll x, ll y) {
        x = find(x);
        y = find(y);
        if (x == y) return;
        if (rank[x] < rank[y]) {
            par[x] = y;
            size[y] += size[x];
        } else {
            par[y] = x;
            size[x] += size[y];
            if (rank[x] == rank[y]) rank[x]++;
        }
    }

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

// get size of tree
    ll UnionFind::getsize(ll x) {
        return size[find(x)];
    }

// get the number of roots
    int UnionFind::rootCount() {
        int cnt = 0;
        for (int i = 0; i < n; i++) {
            if (i == par[i]) cnt++;
        }
        return cnt;
    }


// verify
// https://atc001.contest.atcoder.jp/tasks/unionfind_a

}

#endif //DEFINE_UNIONFIND_HPP
using unionfind::UnionFind;

class CInterpretation {
public:
	void solve(std::istream& in, std::ostream& out) {
        int n, m;
        in >> n >> m;
        UnionFind uf(n+m);
        for(int i=0; i<n; i++){
            int k, l;
            in >> k;
            for(int j=0; j<k; j++){
                in >> l;
                uf.unite(--l, m+i);
            }
        }

        bool flg = true;
        for(int i=0; i<n-1; i++){
            if(!uf.same(m+i, m+i+1)) flg = false;
        }

        bl2(flg, out);
	}
};


int main() {
	CInterpretation solver;
	std::istream& in(std::cin);
	std::ostream& out(std::cout);
	solver.solve(in, out);
	return 0;
}


Measured memory_bytes: 4992