import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.HashSet;
import java.util.StringTokenizer;

/*
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 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */

/**
 *
 * @author cteam014
 */
public class Icecream {
    BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
    StringTokenizer tokenizer;
    String[] input;
    
    
    public void solve() throws  Exception {
        String line;
        while ((line = reader.readLine()) != null) {
            int minimum = -1;
            tokenizer = new StringTokenizer(line);
            String[] nums = line.split(" ");
            int N = Integer.parseInt(nums[0]); //             int N = Integer.parseInt(nums[0]); //
            int K = Integer.parseInt(nums[1]); //tokenizer.nextToken()
            input = new String[N];
            
            for (int i = 0; i < N; i++) {
                input[i] = reader.readLine();
            }
            
            int[] trues = new int[N];
            int[] numSaples = new int[N];
            boolean[][] dpMatrix = new boolean[N][K];
            
            long iters = 0;
            long end = ((long)N)*((long)N);
            int stand = 0;
            while (trues[N - 1] < K && iters < end) {
                iters++;

                if (trues[stand % N] >= K) {
                    continue;
                }
                
                tokenizer = new StringTokenizer(input[stand % N]);
                int L = Integer.parseInt(tokenizer.nextToken());
                HashSet<Integer> samples = new HashSet<>();
                
                for (int i = 0; i < L; i++) {
                    int sample = Integer.parseInt(tokenizer.nextToken());
                    samples.add(sample - 1);
                }

                for (int i = stand; i <= stand + N; i++) {
                    numSaples[i % N] += L;
                    for (int sample : samples) {
                        
                        
                        if (! dpMatrix[i % N][sample]) {
                            dpMatrix[i % N][sample] = true;
                            trues[i % N]++;
                        }
                    }
                    
                    
                    if (trues[i % N] >= K) {
                        if ((minimum > 0 && numSaples[i % N] < minimum) || minimum < 0) {
                            minimum = numSaples[i % N];
                        }
                    }
                    
                }
                
                ++stand;
            }
            
            if (minimum < 0) {
                System.out.println(minimum);
            } else {
                System.out.println(minimum - 1);
            }
            
        }   
    }
    
    public static void main(String[] args) throws Exception {
        new Icecream().solve();
        //long a = 100000;
        //System.out.println(a*a);
    }
}