import java.util.*;
import java.io.*;
 
public class Main {
    static int ans = 0;
    public static void main(String[] args) throws Exception {
        FastScanner sc = new FastScanner(System.in);
        int n = sc.nextInt();
        int m = sc.nextInt();
        ArrayList<ArrayList<Integer>> li = new ArrayList<>();
        for(int i = 0; i < m; i++){
            li.add(new ArrayList<Integer>());
        }
        for(int i = 0; i < n; i++){
            int k = sc.nextInt();
            for(int j = 0; j < k; j++){
                li.get(sc.nextInt()-1).add(i);
            }
        }
        UnionFindTree uf = new UnionFindTree(n);
        for(ArrayList<Integer> l2 : li){
            if(l2.size() == 0) continue;
            int hub = l2.get(0);
            for(int i = 1; i < l2.size(); i++){
                uf.union(hub,l2.get(i));
            }
        }
        System.out.println(uf.size(0) == n ? "YES" : "NO");
    }
}

class UnionFindTree {
	int[] parent;
	int[] rank;
	int[] size;
	
	public UnionFindTree(int size) {
		this.parent = new int[size];
		this.rank = new int[size];
		this.size = new int[size];
		
		for (int i = 0; i < size; i++) {
			makeSet(i);
		}
	}
	
	public void makeSet(int i) {
		parent[i] = i;
		rank[i] = 0;
		size[i] = 1;
	}
	
	public void union(int x, int y) {
		int xRoot = find(x);
		int yRoot = find(y);
		
		if (rank[xRoot] > rank[yRoot]) { 
			parent[yRoot] = xRoot;
			size[xRoot] += size[yRoot];
		} else if(rank[xRoot] < rank[yRoot]) {
			parent[xRoot] = yRoot;
			size[yRoot] += size[xRoot];
		} else if (xRoot != yRoot){
			parent[yRoot] = xRoot;
			size[xRoot] += size[yRoot];
			rank[xRoot]++; 
		}
	}
	
	public int find(int i) {
		if (i != parent[i]) {
			parent[i] = find(parent[i]);
		}
		return parent[i];
	}
	
	public boolean same(int x, int y) {
		return find(x) == find(y);
	}

	public int size(int x) {
		return size[find(x)];
	}
}

class FastScanner {
    private BufferedReader reader = null;
    private StringTokenizer tokenizer = null;
    public FastScanner(InputStream in) {
        reader = new BufferedReader(new InputStreamReader(in));
        tokenizer = null;
    }
    
    public void close() throws Exception{
        this.reader.close();
        return;
    }

    public String next() {
        if (tokenizer == null || !tokenizer.hasMoreTokens()) {
            try {
                tokenizer = new StringTokenizer(reader.readLine());
            } catch (IOException e) {
                throw new RuntimeException(e);
            }
        }
        return tokenizer.nextToken();
    }

    public String nextLine() {
        if (tokenizer == null || !tokenizer.hasMoreTokens()) {
            try {
                return reader.readLine();
            } catch (IOException e) {
                throw new RuntimeException(e);
            }
        }
        return tokenizer.nextToken("\n");
    }

    public long nextLong() {
        return Long.parseLong(next());
    }

    public int nextInt() {
        return Integer.parseInt(next());
    }

    public double nextDouble() {
         return Double.parseDouble(next());
    }

    public int[] nextIntArray(int n) {
        int[] a = new int[n];
        for (int i = 0; i < n; i++)
            a[i] = nextInt();
        return a;
    }

    public long[] nextLongArray(int n) {
        long[] a = new long[n];
        for (int i = 0; i < n; i++)
            a[i] = nextLong();
        return a;
    } 
}


Measured memory_bytes: 46816