using System;
using static System.Console;
using System.Linq;
using System.Collections.Generic;

class Program
{
    static int NN => int.Parse(ReadLine());
    static int[] NList => ReadLine().Split().Select(int.Parse).ToArray();
    static int[][] NArr(long n) => Enumerable.Repeat(0, (int)n).Select(_ => NList).ToArray();
    public static void Main()
    {
        Solve();
    }
    static void Solve()
    {
        var c = NList;
        var (n, k) = (c[0], c[1]);
        var a = new int[n];
        var b = new int[n][];
        for (var i = 0; i < n; ++i)
        {
            c = NList;
            a[i] = c[0];
            if (c[1] == 0)
            {
                ReadLine();
                b[i] = new int[0];
            }
            else b[i] = NList;
        }
        var dp = new long[n];
        for (var i = 1; i < n; ++i)
        {
            dp[i] = dp[i - 1];
            for (var j = 0; j < b[i].Length; ++j)
            {
                var prev = b[i][j] - 1;
                dp[i] = Math.Max(dp[i], dp[prev] + a[i] - a[prev]);
            }
        }
        WriteLine(dp[n - 1]);
    }
}