const int isDebugMode = 0;
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<long long, long long> P;
struct edge{long long to,cost;};
const int inf = 1 << 27;
const long long INF = 1LL << 60;
const int COMBMAX = 1001001;
const long long MOD = 1000000007;
const long long dy[] = {-1, 0, 0, 1};
const long long dx[] = {0, -1, 1, 0};
string abc = "abcdefghijklmnopqrstuvwxyz";
#define rep(i,n) for(int i = 0; i < (n); ++i)
#define eachdo(v, e) for (const auto &e : (v))
#define all(v) (v).begin(), (v).end()
#define lower_index(v, e) (long long)distance((v).begin(), lower_bound((v).begin(), (v).end(), e))
#define upper_index(v, e) (long long)distance((v).begin(), upper_bound((v).begin(), (v).end(), e))
long long mpow(long long a, long long n, long long mod = MOD){long long res = 1; while(n > 0){if(n & 1)res = res * a % mod; a = a * a % mod; n >>= 1;} return res;}
void pt(){cout << endl; return;}
template<class Head> void pt(Head&& head){cout << head; pt(); return;}
template<class Head, class... Tail> void pt(Head&& head, Tail&&... tail){cout << head << " "; pt(forward<Tail>(tail)...);}
void dpt(){if(!isDebugMode) return; cout << endl; return;}
template<class Head> void dpt(Head&& head){if(!isDebugMode) return; cout << head; pt(); return;}
template<class Head, class... Tail> void dpt(Head&& head, Tail&&... tail){if(!isDebugMode) return; cout << head << " "; pt(forward<Tail>(tail)...);}
template<class T> void debug(T v){if(!isDebugMode) return; rep(i, v.size()) cout << v[i] << " " ; cout << endl;}
template<class T> void debug2(T v){if(!isDebugMode) return; rep(i, v.size()){rep(j, v[i].size()) cout << v[i][j] << " " ; cout << endl;}}
template<class T1, class T2> inline bool chmin(T1 &a, T2 b){if(a > b){a = b; return true;} return false;}
template<class T1, class T2> inline bool chmax(T1 &a, T2 b){if(a < b){a = b; return true;} return false;}
template<class T1, class T2> long long gcd(T1 a, T2 b){return a % b ? gcd(b , a % b) : b;}
template<class T1, class T2> void reduce(T1 &a, T2 &b){ll g = gcd(a, b); a /= g; b /= g; return;}
bool valid(long long H, long long W, long long h, long long w) { return 0 <= h && h < H && 0 <= w && w < W; }

class UnionFind {
public:
    vector <ll> par;
    vector <ll> siz;

    UnionFind(ll sz_): par(sz_), siz(sz_, 1LL) {
        for (ll i = 0; i < sz_; ++i) par[i] = i;
    }
    void init(ll sz_) {
        par.resize(sz_);
        siz.assign(sz_, 1LL);
        for (ll i = 0; i < sz_; ++i) par[i] = i;
    }

    ll find(ll x) {
        while (par[x] != x) {
            x = par[x] = par[par[x]];
        }
        return x;
    }

    bool merge(ll x, ll y) {
        x = find(x);
        y = find(y);
        if (x == y) return false;
        if (siz[x] < siz[y]) swap(x, y);
        siz[x] += siz[y];
        par[y] = x;
        return true;
    }

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

    ll size(ll x) {
        return siz[find(x)];
    }
};


int main(){
    ll N, M; cin >> N >> M;
    UnionFind uf(M);
    vector<vector<ll>> list(N, vector<ll>());
    set<ll> aped;
    rep(i, N){
        ll k; cin >> k;
        rep(j, k){
            ll a; cin >> a;
            --a;
            aped.insert(a);
            list[i].push_back(a); 
        }
        rep(j, list[i].size() - 1){
            uf.merge(list[i][j], list[i][j + 1]);
        }
    }
    ll siz = aped.size();
    bool ok = true;
    rep(i, N){
        bool ex = false;
        rep(j, list[i].size()){
            dpt(i, j, uf.size(list[i][j]));
            if(uf.size(list[i][j]) == siz) ex = true;
        }
        if(!ex) ok = false;
    }
    pt(ok ? "YES" : "NO");
    return 0;
}

Measured memory_bytes: 8320