#include<bits/stdc++.h>

using namespace std;

#define ll long long

const int mod=1e9+7;

int n,m;
int bj[33];
ll dp[5000005];

signed main(){
	ios::sync_with_stdio(0);cin.tie(0);
	cin>>n>>m;
	for(int i=1;i<=m;++i){
		int u,v;cin>>u>>v;
		bj[v]|=(1<<(u-1));
	}
	dp[0]=1;
	for(int i=0;i<(1<<n);++i){
		int cnt=0;
		for(int j=0;j<n;++j){
			cnt+=((i>>j)&1);
		}
		for(int j=0;j<n;++j){
			if(!((i>>j)&1)) continue;
			if(((i^(1<<j))&bj[j+1])!=bj[j+1]) continue;
			dp[i]=(dp[i]+dp[i^(1<<j)])%mod;
		}
	//	cout<<i<<" "<<dp[i]<<'\n';
	}
	cout<<dp[(1<<n)-1]<<'\n';
	return 0;
}