using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.IO;
using System.Text;
using System.Globalization;
using System.Diagnostics;



class Myon
{
    public Myon() { }
    public static int Main()
    {
        new Myon().calc();
        return 0;
    }
    

    Scanner cin;

    int N, M;
    bool[,] edge;

    void calc()
    {
        cin = new Scanner();
        N = cin.nextInt();
        M = cin.nextInt();
        edge = new bool[N, N];

        for (int i = 0; i < M; i++)
        {
            int a = cin.nextInt() - 1;
            int b = cin.nextInt() - 1;
            edge[a, b] = edge[b, a] = true;

        }

        int[] num = new int[N];
        for (int i = 0; i < N; i++)
        {
            num[i] = i;
        }

        int ans = 0;
        do
        {
            bool flag = true;
            if (num[0] != 0) break;
            for (int i = 0; i < N - 1; i++)
            {
                if(!edge[num[i], num[i + 1]])
                {
                    flag = false;
                    break;
                }
            }
            if (flag) ans++;
        } while (next_permutation(num));

        Console.WriteLine(ans);
    }

    public static bool next_permutation<T>(T[] array) where T : IComparable<T>
    {
        return next_permutation(array, 0, array.Length);
    }

    public static bool next_permutation<T>(T[] array, int start, int length) where T : IComparable<T>
    {
        int end = start + length - 1;
        if (end <= start) return false;
        int last = end;
        while (true)
        {
            int pos = last--;
            if (array[last].CompareTo(array[pos]) < 0)
            {
                int i;
                for (i = end + 1; array[last].CompareTo(array[--i]) >= 0;) { }
                T tmp = array[last]; array[last] = array[i]; array[i] = tmp;
                Array.Reverse(array, pos, end - pos + 1);
                return true;
            }
            if (last == start)
            {
                //Array.Reverse(array, start, end - start);
                return false;
            }
        }
    }


}


class Scanner
{
    string[] s;
    int i;

    char[] cs = new char[] { ' ' };

    public Scanner()
    {
        s = new string[0];
        i = 0;
    }

    public string next()
    {
        if (i < s.Length) return s[i++];
        string st = Console.ReadLine();
        while (st == "") st = Console.ReadLine();
        s = st.Split(cs, StringSplitOptions.RemoveEmptyEntries);
        if (s.Length == 0) return next();
        i = 0;
        return s[i++];
    }

    public int nextInt()
    {
        return int.Parse(next());
    }
    public int[] ArrayInt(int N, int add = 0)
    {
        int[] Array = new int[N];
        for (int i = 0; i < N; i++)
        {
            Array[i] = nextInt() + add;
        }
        return Array;
    }

    public long nextLong()
    {
        return long.Parse(next());
    }

    public long[] ArrayLong(int N, long add = 0)
    {
        long[] Array = new long[N];
        for (int i = 0; i < N; i++)
        {
            Array[i] = nextLong() + add;
        }
        return Array;
    }

    public double nextDouble()
    {
        return double.Parse(next());
    }


    public double[] ArrayDouble(int N, double add = 0)
    {
        double[] Array = new double[N];
        for (int i = 0; i < N; i++)
        {
            Array[i] = nextDouble() + add;
        }
        return Array;
    }
}


Measured memory_bytes: 11220