#include<bits/stdc++.h>
#define endl '\n'
using namespace std;
const int MAXN = 12, MAXM = 200;
void speed()
{
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cout.tie(NULL);
}
int n, m;
int from[MAXM], to[MAXM];
void read()
{
cin >> n >> m;
for (int i = 1; i <= m; ++ i)
cin >> from[i] >> to[i];
}
int order[MAXN], used[MAXN], visited[MAXN], in_cycle[MAXN]; /// na koq poziciq e i
int ans = 0, imp = 0;
const int mod = 998244353;
unordered_set < long long > mp;
vector < int > g[MAXN];
void dfs(int beg)
{
if(imp)return;
visited[beg] = 1;
in_cycle[beg] = 1;
for (auto nb: g[beg])
{
if(imp)return;
if(!visited[nb])dfs(nb);
else if(in_cycle[nb])imp = 1;
}
in_cycle[beg] = 0;
}
void check()
{
int cnt = 0;
long long curr = 0;
for (int i = 1; i <= m; ++ i)
{
if(order[from[i]] > order[to[i]])
curr = curr;
else
curr = curr + (1 << (i-1));
}
if(mp.find(curr) != mp.end())return;
mp.insert(curr);
for (int i = 1; i <= n; ++ i)
{
g[i].clear();
visited[i] = 0;
in_cycle[i] = 0;
}
for (int i = 1; i <= m; ++ i)
{
if(order[from[i]] > order[to[i]])g[from[i]].push_back(to[i]);
else
{
cnt ++;
g[to[i]].push_back(from[i]);
}
}
imp = 0;
for (int i = 1; i <= n && (!imp); ++ i)
{
if(visited[order[i]])continue;
dfs(visited[order[i]]);
}
if(imp)return;
ans += cnt;
}
void gen(int pos)
{
if(pos > n)
{
check();
return;
}
for (int i = 1; i <= n; ++ i)
{
if(used[i])continue;
order[pos] = i;
used[i] = 1;
gen(pos+1);
used[i] = 0;
}
}
int main()
{
speed();
read();
gen(1);
cout << ans << endl;
return 0;
}
