//Nguyen Huu Hoang Minh
#include <bits/stdc++.h>
#define sz(x) int(x.size())
#define all(x) x.begin(),x.end()
#define reset(x) memset(x, 0,sizeof(x))
#define pb push_back
#define mp make_pair
#define fi first
#define se second
#define N 25
#define remain(x) if (x > MOD) x -= MOD
#define ii pair<int, int>
#define iiii pair< ii , ii >
#define viiii vector< iiii >
#define vi vector<int>
#define vii vector< ii >
#define bit(x, i) (((x) >> (i)) & 1)
#define Task "test"
#define int long long

using namespace std;

typedef long double ld;
const int inf = 1e10;
const int minf = -1e10;
const int Mod = 1e9+7;

int n, m;
vector<int> g[N];

void readfile()
{
    ios_base::sync_with_stdio(false);
    cin.tie(0);cout.tie(0);
    if (fopen(Task".inp","r"))
    {
        freopen(Task".inp","r",stdin);
        //freopen(Task".out","w",stdout);
    }
    cin >> n >> m;
    for(int i=1; i<=m; i++){
        int u, v;
        cin >> u >> v;
        u--; v--;
        g[u].pb(v);
    }
}

int num[1<<20][21];

void proc()
{
    int nn = (1<<n);
    memset(num, 0, sizeof num);
    num[1][0] = 1;
    for(int msk=1; msk<nn; msk++){
        if (num[msk]==0) continue;
        for(int i=0; i<n; i++){
            if (bit(msk,i)){
                for(int v : g[i]){
                    if (bit(msk,v)) continue;
                    int nmsk = msk | (1<<v);
                    num[nmsk][v] = (num[nmsk][v]+num[msk][i])%Mod;
                }
            }
        }
    }
    cout << num[nn-1][n-1];
}

signed main()
{
    readfile();
    proc();
    return 0;
}