#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define pb push_back
#define ff first
#define ss second
#define all(s) s.begin(),s.end()
#define rall(s) s.rbegin(),s.rend()
int main(){
ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
ll n,m;
cin>>n>>m;
ll g[n+5];
vector<pair<ll,ll>>edge;
for(ll i=1;i<=m;i++){
ll a,b;
cin>>a>>b;
edge.pb({a,b});
}
ll p[n+5],pos[n+5];
iota(p+1,p+n+1,1);
vector<ll>v;
do{
for(ll i=1;i<=n;i++){
pos[p[i]]=i;
}
ll num=0,cnt=0;
for(ll i=0;i<m;i++){
auto [a,b]=edge[i];
if(pos[a]>pos[b]){
num|=(1ll<<i);
}
}
v.pb(num);
}while(next_permutation(p+1,p+n+1));
sort(all(v));
v.erase(unique(all(v)),v.end());
ll ans=0;
for(ll x:v){
ans+=__builtin_popcountll(x);
}
cout<<ans;
}
