/*****/

#include <iostream>
#include <array>
#include <vector>
#include <algorithm>
#include <string>
#include <cmath>
#include <queue>
#include <stack>
#include <map>
#include <iomanip>	//cout << fixed << setprecision(桁数);
#include <stdexcept>

//#define int long long

using namespace std;
using ll = long long;
using ld = long double;

#define nextline() (std::cerr << "\n")
#define debug(x) (#x " : " + (x))
#define debug_cout(x) (std::cerr << #x << " : " <<  (x) << "\n")
#define debug_tabcout(n, x) (std::cerr << strMulti("\t",n) << #x << " : " <<  (x) << "\n")
#define debug_headcout(h, x) (std::cerr << h << " : " <<  (x) << "\n")
#define debug_tabheadcout(n, h, x) (std::cerr << strMulti("\t",n) << h << " : " <<  (x) << "\n")

#define rep(i, n) for(int i=0, i##_len=(n); i<i##_len; ++i)
#define rep1(i, n) for(int i=1, i##_len=(n); i<=i##_len; ++i)
#define rrep(i, n) for(int i=(n)-1; i >= 0; --i)
#define rrep1(i, n) for(int i=(n); i > 0; --i)
#define all(x) (x).begin(), (x).end()
#define pair(a, b) make_pair(a, b);
constexpr int INF = 2000000100;
constexpr ll DIV = 1000000007;	// 10e9+7
template<class T> bool chmax(T& a, T b) { if (a < b) { a = b; return true; } return false; }
template<class T> bool chmin(T& a, T b) { if (a > b) { a = b; return true; } return false; }
//template<class T> T divup(T a, T b) { if (a % b == 0) { return a / b; } return a / b + 1; }
#define divup(a, b) ((a) % (b) == 0 ? (a) / (b) : (a) / (b) + 1)
#define exist_in(list, value) (list.end() != std::find(all(list),value))
std::string strMulti(std::string t, int n) { std::string out = ""; for (int i = 0; i < n; i++) { out += t; } return out; }
//template<class T> T math_P(T m, T n) { T ret = 1; for (T i = m; i > m - n; i--) { ret *= i; } return ret; }
//template<class T> T math_C(T m, T n) { T ret = mathP(m, n); for (T i = 2; i <= n; i++) { ret /= i; } return ret; }
//template<class T> bool compare_by_b(pair<T, T> a, pair<T, T> b) { if (a.second != b.second) { return a.second < b.second; } return a.first < b.first; }
//template<class T> T math_gcd(T a, T b) { a = abs(a); b = abs(b); if (a < b) { std::swap(a, b); } T tmp; while (b != 0) { tmp = b; b = a % b; a = tmp; } return a; }
//template<class T> T math_lcm(T a, T b) { a = abs(a); b = abs(b); if (a > b) { std::swap(a, b); } if (a == 1) { return b; } T i = a; while (i % b != 0) { i += a; } return i; }
//template<class T1, class T2> bool exist_in(const T1& list, const T2& v) { return (list.end() != std::find(list.begin(), list.end(), v)); }
//template<class T> bool exist_in(const T& c, const typename T::value_type& v) {	return (c.end() != std::find(c.begin(), c.end(), v));}

/*****/

int n, m;
vector<vector<int>> g;

void dfs(int v, vector<bool>& seen, int& res)
{
	bool end = true;
	rep(i, seen.size())
	{
		if (!seen[i] && i != v)	end = false;
	}
	if (end) { ++res; return; }

	seen[v] = true;
	for (auto nv : g[v])
	{
		if (seen[nv])	continue;
		dfs(nv, seen, res);
	}
	seen[v] = false;
}

void Main()
{
	cin >> n >> m;
	g.assign(n, vector<int>());
	rep(i, m)
	{
		int a, b;
		cin >> a >> b;
		--a; --b;
		g[a].push_back(b);
		g[b].push_back(a);
	}

	vector<bool> seen(n, false);
	int res = 0;
	dfs(0, seen, res);
	cout << res << endl;
}

/*****/

int main()
{
	//std::ios::sync_with_stdio(false);
	//std::cin.tie(0);

	std::cout << std::fixed << std::setprecision(10);


	/*
	while (true)
	{
		Main();
		cout << endl;
	}
	//*/


	Main();

	return 0;
}


Measured memory_bytes: 256