Problem:
Score : 200 points

Problem Statement

Katsusando loves omelette rice.

Besides, he loves crème brûlée, tenderloin steak and so on, and believes that these foods are all loved by everyone.

To prove that hypothesis, he conducted a survey on M kinds of foods and asked N people whether they like these foods or not.

The i-th person answered that he/she only likes the A_{i1}-th, A_{i2}-th, ..., A_{iK_i}-th food.

Find the number of the foods liked by all the N people.

Constraints

All values in input are integers.

1 \leq N, M \leq 30

1 \leq K_i \leq M

1 \leq A_{ij} \leq M

For each i (1 \leq i \leq N), A_{i1}, A_{i2}, ..., A_{iK_i} are distinct.

Constraints

Input is given from Standard Input in the following format:

N M
K_1 A_{11} A_{12} ... A_{1K_1}
K_2 A_{21} A_{22} ... A_{2K_2}
:
K_N A_{N1} A_{N2} ... A_{NK_N}

Output

Print the number of the foods liked by all the N people.

Sample Input 1

3 4
2 1 3
3 1 2 3
2 3 2

Sample Output 1

1

As only the third food is liked by all the three people, 1 should be printed.

Sample Input 2

5 5
4 2 3 4 5
4 1 3 4 5
4 1 2 4 5
4 1 2 3 5
4 1 2 3 4

Sample Output 2

0

Katsusando's hypothesis turned out to be wrong.

Sample Input 3

1 30
3 5 10 30

Sample Output 3

3

Solution in C# (Mono 4.6.2.0) (judge verdict: Accepted)

using System;
using System.Collections.Generic;
using System.Linq;
using BitArray = System.Collections.BitArray;
using BigInteger = System.Numerics.BigInteger;

namespace AtCoderProject
{
    public class Program
    {
        public object Calc()
        {
            var line = consoleReader.SplitInt32();
            var N = line[0];
            var M = line[1];

            var lines = consoleReader.RepeatSplitInt32(N).Select(ia => ia.Skip(1).ToArray()).ToArray();

            IEnumerable<int> r = lines[0];
            foreach (var l in lines.Skip(1))
            {
                r = r.Intersect(l);
            }

            return r.Count();
        }

        const int mod = 1000000007;
        private readonly ConsoleReader consoleReader;
        public Program() : this(new ConsoleReader()) { }
        public Program(ConsoleReader consoleReader) { this.consoleReader = consoleReader; }
        static void Main() => Console.WriteLine(new Program().Calc());
        public static string MultiLine<T>(IEnumerable<T> source) => string.Join("\n", source);
    }

    public class ConsoleReader
    {
        public virtual string String() => Console.ReadLine();
        public int Int32() => int.Parse(String());
        public long Int64() => long.Parse(String());
        public ulong UInt64() => ulong.Parse(String());
        public double Double() => double.Parse(String());
        public string[] Split() => String().Split().ToArray();
        public int[] SplitInt32() => String().Split().Select(int.Parse).ToArray();
        public long[] SplitInt64() => String().Split().Select(long.Parse).ToArray();
        public ulong[] SplitUInt64() => String().Split().Select(ulong.Parse).ToArray();
        public double[] SplitDouble() => String().Split().Select(double.Parse).ToArray();

        public IEnumerable<string> Repeat(int count)
        {
            for (int i = 0; i < count; i++)
                yield return String();
        }
        public IEnumerable<int> RepeatInt32(int count)
        {
            for (int i = 0; i < count; i++)
                yield return Int32();
        }
        public IEnumerable<long> RepeatInt64(int count)
        {
            for (int i = 0; i < count; i++)
                yield return Int64();
        }
        public IEnumerable<string[]> RepeatSplit(int count)
        {
            for (int i = 0; i < count; i++)
                yield return Split();
        }
        public IEnumerable<int[]> RepeatSplitInt32(int count)
        {
            for (int i = 0; i < count; i++)
                yield return SplitInt32();
        }
    }
}