#include <bits/stdc++.h>
#define fo(i, d, c) for (int i = d; i <= c; i++)
#define fod(i, c, d) for (int i = c; i >= d; i--)
#define maxn 1000010
#define N 1010
#define fi first
#define se second
#define pb emplace_back
#define en cout << "\n";
#define int long long
#define inf (int)1e18
#define bitcount(x) __builtin_popcountll(x)
#define pii pair<int, int>
#define vii vector<pii>
#define lb(x) x & -x
#define bit(i, j) ((i >> j) & 1)
#define offbit(i, j) (i ^ (1LL << j))
#define onbit(i, j) (i | (1LL << j))
#define vi vector<int>
#define all(x) x.begin(), x.end()
#define ss(x) (int)x.size()
#define UNIQUE(v) v.erase(unique(all(v)), v.end())
template <typename T1, typename T2>
bool minimize(T1 &a, T2 b)
{
if (a > b)
{
a = b;
return true;
}
return false;
}
template <typename T1, typename T2>
bool maximize(T1 &a, T2 b)
{
if (a < b)
{
a = b;
return true;
}
return false;
}
using namespace std;
const int nsqrt = 450;
const int mod = 1e9 + 7;
void add(int &x, int k)
{
x += k;
x %= mod;
if (x < 0)
x += mod;
}
void del(int &x, int k)
{
x -= k;
x %= mod;
if (x < 0)
x += mod;
}
int n, m;
pii a[N];
int id[20],pos[20];
main()
{
#define name "TASK"
if (fopen(name ".inp", "r"))
{
freopen(name ".inp", "r", stdin);
freopen(name ".out", "w", stdout);
}
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cin >> n >> m;
fo(i, 0, m - 1) cin >> a[i].fi >> a[i].se;
fo(i, 1, n) id[i] = i;
set<int> st;
do
{
fo(i,1,n) pos[id[i]] = i;
int mask = 0;
fo(i,0,m - 1)
{
auto [u,v] = a[i];
if(pos[u] > pos[v]) mask = onbit(mask,i);
}
st.insert(mask);
} while (next_permutation(id + 1, id + n + 1));
int ans = 0;
for(int it : st) ans += bitcount(it);
cout << ans;
}
