Problem:
Score : 500 points

Problem Statement

We have N locked treasure boxes, numbered 1 to N.

A shop sells M keys. The i-th key is sold for a_i yen (the currency of Japan), and it can unlock b_i of the boxes: Box c_{i1}, c_{i2}, ..., c_{i{b_i}}. Each key purchased can be used any number of times.

Find the minimum cost required to unlock all the treasure boxes. If it is impossible to unlock all of them, print -1.

Constraints

All values in input are integers.

1 \leq N \leq 12

1 \leq M \leq 10^3

1 \leq a_i \leq 10^5

1 \leq b_i \leq N

1 \leq c_{i1} < c_{i2} < ... < c_{i{b_i}} \leq N

Input

Input is given from Standard Input in the following format:

N M
a_1 b_1
c_{11} c_{12} ... c_{1{b_1}}
:
a_M b_M
c_{M1} c_{M2} ... c_{M{b_M}}

Output

Print the minimum cost required to unlock all the treasure boxes.
If it is impossible to unlock all of them, print -1.

Sample Input 1

2 3
10 1
1
15 1
2
30 2
1 2

Sample Output 1

25

We can unlock all the boxes by purchasing the first and second keys, at the cost of 25 yen, which is the minimum cost required.

Sample Input 2

12 1
100000 1
2

Sample Output 2

-1

We cannot unlock all the boxes.

Sample Input 3

4 6
67786 3
1 3 4
3497 1
2
44908 3
2 3 4
2156 3
2 3 4
26230 1
2
86918 1
3

Sample Output 3

69942

Solution in Java8 (OpenJDK 1.8.0) (judge verdict: Time Limit Exceeded)

import java.io.InputStream;
import java.io.PrintStream;
import java.util.Arrays;
import java.util.Scanner;

public class Main {
	InputStream in = System.in;
	PrintStream out = System.out;

	long[] p;
	int[] a, b;
	int[][] c;
	int N, M;

	private int rec(int i, long t) { //i以降でtの箱をあけられる鍵の買い方の、最小金額
		if (t == 0) {
			return 0;
		}
		if (i == M) {
			return -1;
		}

		//i番目を買う
		int z1 = rec(i + 1, t & (~p[i]));
		int z2 = a[i] + z1;
		if (z1 == -1) {
			z2 = Integer.MAX_VALUE;
		}

		//i番目を買わない
		int y = rec(i + 1, t);

		if (z1 == -1 && y == -1) {
			return -1;
		}
		if (y == -1) {
			y = Integer.MAX_VALUE;
		}

		return Math.min(z2, y);

	}

	public void _main(String[] args) {
		Scanner sc = new Scanner(in);

		N = sc.nextInt();
		M = sc.nextInt();

		a = new int[M];
		b = new int[M];
		c = new int[M][];

		for (int i = 0; i < M; i++) {
			a[i] = sc.nextInt();
			b[i] = sc.nextInt();
			c[i] = nextIntArray(sc, b[i]);
		}

		sc.close();

		p = new long[M];
		for (int i = 0; i < M; i++) {
			for (int j = 0; j < c[i].length; j++) {
				p[i] |= ((long) 1 << (c[i][j] - 1));
			}
		}

		int ans = rec(0, (1 << N) - 1);
		out.println(ans);
	}

	public static void main(String[] args) {
		new Main()._main(args);
	}

	@SuppressWarnings("unused")
	private int[] nextIntArray(Scanner sc, int n) {
		int[] result = new int[n];
		for (int i = 0; i < n; i++) {
			result[i] = sc.nextInt();
		}
		return result;
	}
}