#include<bits/stdc++.h>
using namespace std;

#define REP(i,a,b) for(i=a;i<b;i++)
#define rep(i,n) REP(i,0,n)

#define mygc(c) (c)=getchar_unlocked()
#define mypc(c) putchar_unlocked(c)

#define ll long long
#define ull unsigned ll

void reader(int *x){int k,m=0;*x=0;for(;;){mygc(k);if(k=='-'){m=1;break;}if('0'<=k&&k<='9'){*x=k-'0';break;}}for(;;){mygc(k);if(k<'0'||k>'9')break;*x=(*x)*10+k-'0';}if(m)(*x)=-(*x);}
void reader(ll *x){int k,m=0;*x=0;for(;;){mygc(k);if(k=='-'){m=1;break;}if('0'<=k&&k<='9'){*x=k-'0';break;}}for(;;){mygc(k);if(k<'0'||k>'9')break;*x=(*x)*10+k-'0';}if(m)(*x)=-(*x);}
void reader(double *x){scanf("%lf",x);}
int reader(char c[]){int i,s=0;for(;;){mygc(i);if(i!=' '&&i!='\n'&&i!='\r'&&i!='\t'&&i!=EOF) break;}c[s++]=i;for(;;){mygc(i);if(i==' '||i=='\n'||i=='\r'||i=='\t'||i==EOF) break;c[s++]=i;}c[s]='\0';return s;}
template <class T, class S> void reader(T *x, S *y){reader(x);reader(y);}
template <class T, class S, class U> void reader(T *x, S *y, U *z){reader(x);reader(y);reader(z);}
template <class T, class S, class U, class V> void reader(T *x, S *y, U *z, V *w){reader(x);reader(y);reader(z);reader(w);}

void writer(int x, char c){int s=0,m=0;char f[10];if(x<0)m=1,x=-x;while(x)f[s++]=x%10,x/=10;if(!s)f[s++]=0;if(m)mypc('-');while(s--)mypc(f[s]+'0');mypc(c);}
void writer(ll x, char c){int s=0,m=0;char f[20];if(x<0)m=1,x=-x;while(x)f[s++]=x%10,x/=10;if(!s)f[s++]=0;if(m)mypc('-');while(s--)mypc(f[s]+'0');mypc(c);}
void writer(double x, char c){printf("%.15f",x);mypc(c);}
void writer(const char c[]){int i;for(i=0;c[i]!='\0';i++)mypc(c[i]);}
void writer(const char x[], char c){int i;for(i=0;x[i]!='\0';i++)mypc(x[i]);mypc(c);}
template<class T> void writerLn(T x){writer(x,'\n');}
template<class T, class S> void writerLn(T x, S y){writer(x,' ');writer(y,'\n');}
template<class T, class S, class U> void writerLn(T x, S y, U z){writer(x,' ');writer(y,' ');writer(z,'\n');}
template<class T> void writerArr(T x[], int n){int i;if(!n){mypc('\n');return;}rep(i,n-1)writer(x[i],' ');writer(x[n-1],'\n');}

char memarr[17000000]; void *mem = memarr;
#define MD 1000000007

int get_inv(ll a, int md){ll t=a,s=md,u=1,v=0,e;while(s){e=t/s;t-=e*s;u-=e*v;swap(t,s);swap(u,v);}if(u<0)u+=md;return u;}

struct mint{
  static unsigned md, W, R, Rinv, mdninv, RR;
  unsigned val;

  mint(){}mint(int a){val=mulR(a);}mint(unsigned a){val=mulR(a);}mint(ll a){val=mulR(a);}mint(ull a){val=mulR(a);}
  unsigned setmod(unsigned m){int i;unsigned t;W=32;md=m;R=(1ULL<<W)%md;RR=(ull)R*R%md;switch(m){case 104857601:Rinv=2560000;mdninv=104857599;break;case 998244353:Rinv=232013824;mdninv=998244351;break;case 1000000007:Rinv=518424770;mdninv=2226617417U;break;case 1000000009:Rinv=171601999;mdninv=737024967;break;case 1004535809:Rinv=234947584;mdninv=1004535807;break;case 1007681537:Rinv=236421376;mdninv=1007681535;break;case 1012924417:Rinv=238887936;mdninv=1012924415;break;case 1045430273:Rinv=254466304;mdninv=1045430271;break;case 1051721729:Rinv=257538304;mdninv=1051721727;break;default:Rinv=get_inv(R,md);mdninv=0;t=0;rep(i,W){if(t%2==0)t+=md,mdninv|=(1U<<i);t/=2;}}}
  unsigned mulR(unsigned a){return(ull)a*R%md;}unsigned mulR(int a){if(a<0)a=a%md+md;return mulR((unsigned)a);}unsigned mulR(ull a){return mulR((unsigned)(a%md));}unsigned mulR(ll a){if(a<0)a=a%md+md;return mulR((unsigned)a);}
  unsigned reduce(unsigned T){unsigned m=T*mdninv;unsigned t=(unsigned)((T+(ull)m*md)>>W);if(t>=md)t-=md;return t;}unsigned reduce(ull T){unsigned m=(unsigned)T*mdninv;unsigned t=(unsigned)((T+(ull)m*md)>>W);if(t>=md)t-=md;return t;}
  unsigned get(){return reduce(val);}
  mint&operator+=(mint a){val+=a.val;if(val>=md)val-=md;return*this;}mint&operator-=(mint a){if(val<a.val)val=val+md-a.val;else val-=a.val;return*this;}mint&operator*=(mint a){val=reduce((ull)val*a.val);return*this;}mint&operator/=(mint a){return*this*=a.inverse();}
  mint operator+(mint a){return mint(*this)+=a;}mint operator-(mint a){return mint(*this)-=a;}mint operator*(mint a){return mint(*this)*=a;}mint operator/(mint a){return mint(*this)/=a;}
  mint operator+(int a){return mint(*this)+=mint(a);}mint operator-(int a){return mint(*this)-=mint(a);}mint operator*(int a){return mint(*this)*=mint(a);}mint operator/(int a){return mint(*this)/=mint(a);}
  mint operator+(ll a){return mint(*this)+=mint(a);}mint operator-(ll a){return mint(*this)-=mint(a);}mint operator*(ll a){return mint(*this)*=mint(a);}mint operator/(ll a){return mint(*this)/=mint(a);}
  mint operator-(void){mint res;if(val)res.val=md-val;else res.val=0;return res;}
  operator bool(void){return val!=0;}operator int(void){return get();}operator ll(void){return get();}
  mint inverse(){int a=val,b=md,u=1,v=0,t;mint r;while(b){t=a/b;a-=t*b;swap(a,b);u-=t*v;swap(u,v);}if(u<0)u+=md;r.val=(ull)u*RR%md;return r;}
  mint pw(ull b){mint a(*this),r;r.val=R;while(b){if(b&1)r*=a;b>>=1;a*=a;}return r;}
  bool operator==(int a){return get()==a;}
  bool operator!=(int a){return get()!=a;}
};
unsigned mint::md, mint::W, mint::R, mint::Rinv, mint::mdninv, mint::RR;
mint operator+(int a, mint b){return mint(a)+=b;}mint operator-(int a, mint b){return mint(a)-=b;}mint operator*(int a, mint b){return mint(a)*=b;}mint operator/(int a, mint b){return mint(a)/=b;}
mint operator+(ll a, mint b){return mint(a)+=b;}mint operator-(ll a, mint b){return mint(a)-=b;}mint operator*(ll a, mint b){return mint(a)*=b;}mint operator/(ll a, mint b){return mint(a)/=b;}

mint mval[10000], minv[10000];
void mint_init(int md=MD, mint val[]=mval, int vals=10000, mint inv[]=minv, int invs=10000){int i;val[0].setmod(md);val[0].val=0;REP(i,1,vals){val[i].val=val[i-1].val+mint::R;if(val[i].val >=md)val[i].val-=md;}inv[1].val=1;REP(i,2,invs){inv[i].val=md-((ll)(md/i)*inv[md%i].val%md);}REP(i,1,invs)inv[i].val=(ull)inv[i].val*mint::R%md;}

void unionInit(int d[],int s){int i;rep(i,s)d[i]=i;}
int unionGet(int d[],int n){int t=n,k;while(d[t]!=t)t=d[t];while(d[n]!=n)k=d[n],d[n]=t,n=k;return n;}
int unionConnect(int d[],int a,int b){a=unionGet(d,a);b=unionGet(d,b);if(a==b)return 0;d[a]=b;return 1;}

template<class T> void sort(int N, T a[], void *mem = NULL){sort(a,a+N);}
template<class T1, class T2> void sort(int N, T1 a[], T2 b[], void *mem){int i;pair<T1,T2> *r=(pair<T1, T2>*)mem;rep(i,N)r[i].first=a[i],r[i].second=b[i];sort(r,r+N);rep(i,N)a[i]=r[i].first,b[i]=r[i].second;}
template<class T1, class T2, class T3> void sort(int N, T1 a[], T2 b[], T3 c[], void *mem){int i;pair<T1,pair<T2,T3> > *r=(pair<T1,pair<T2,T3> >*)mem;rep(i,N)r[i].first=a[i],r[i].second.first=b[i],r[i].second.second=c[i];sort(r,r+N);rep(i,N)a[i]=r[i].first,b[i]=r[i].second.first,c[i]=r[i].second.second;}
template<class T1, class T2, class T3, class T4> void sort(int N, T1 a[], T2 b[], T3 c[], T4 d[], void *mem){int i;pair<pair<T1,T2>,pair<T3,T4> > *r=(pair<pair<T1,T2>,pair<T3,T4> >*)mem;rep(i,N)r[i].first.first=a[i],r[i].first.second=b[i],r[i].second.first=c[i],r[i].second.second=d[i];sort(r,r+N);rep(i,N)a[i]=r[i].first.first,b[i]=r[i].first.second,c[i]=r[i].second.first,d[i]=r[i].second.second;}


int N, M;
int A[4100], B[4100];
int deg[4100], sdeg[4100];

int edge[4100][4100], tedge[4100][4100];
mint mat[4100][4100];
mint fact[4100];

int ind[4100], cnv[4100], val[4100];

mint lis[4100]; int sz;

int main(){
  int i, j, k, s;
  int cnt;
  mint res, t;

  mint_init();

  fact[0] = mval[1];
  REP(i,1,4001) fact[i] = fact[i-1] * mval[i];

  reader(&N,&M);
  rep(i,M) reader(A+i,B+i), A[i]--, B[i]--;

  rep(i,M) deg[A[i]]--, deg[B[i]]++;

  cnt = 0;
  rep(i,N){
    if(deg[i]==-1) cnt++;
    if(deg[i]<-1) cnt+=2;
  }
  if(cnt >= 2){ writerLn("0"); return 0; }

  rep(i,N) rep(j,N) edge[i][j] = 1;
  rep(i,M) edge[A[i]][B[i]] = 0;
  if(cnt==1){
    rep(i,N) if(deg[i]==-1) break;
    rep(j,N) if(deg[j]== 1) break;
    edge[i][j]++;
  }

  for(;;){
    rep(i,N){
      rep(j,N) if(edge[i][j]) break;
      if(j==N){
        N--;
        rep(j,N) edge[i][j] = edge[N][j];
        rep(j,N) edge[j][i] = edge[j][N];
        i = -1111;
        break;
      }
    }
    if(i==N) break;
  }

  if(N==0){ writerLn(1); return 0; }

  unionInit(ind, N);
  rep(i,N) rep(j,N) if(edge[i][j]) unionConnect(ind,i,j);
  rep(i,N) if(unionGet(ind,i)!=unionGet(ind,0)) break;
  if(i<N){writerLn(0); return 0; }

  rep(i,N) sdeg[i] = 0;
  rep(i,N) rep(j,N) sdeg[i] += edge[i][j];

  res = 1;
  rep(i,N) res *= fact[sdeg[i]-1];

  rep(i,N) ind[i] = i, val[i] = 0;
  rep(i,N) rep(j,N) if(edge[i][j] != 1) val[i]++;
  sort(N, val, ind, mem);
  rep(i,N) rep(j,N) tedge[i][j] = edge[i][j];
  cnv[N-2] = ind[0];
  rep(i,N-2) cnv[i] = ind[i+1];
  cnv[N-1] = ind[N-1];
  rep(i,N) rep(j,N) edge[i][j] = tedge[cnv[i]][cnv[j]];

  rep(i,N) rep(j,N) mat[i][j] = mval[0];
  rep(i,N) rep(j,N) if(i!=j){
    mat[i][j] -= edge[i][j];
    mat[i][i] += edge[i][j];
  }
//  rep(i,N) mat[i][i] += edge[i][i];


  s = N-1;
  rep(i,s-1) rep(j,s) mat[i][j] -= mat[s-1][j];
  
//  rep(i,N){ rep(j,N) printf("%d ",(int)mat[i][j]); puts(""); } puts("");
  
  rep(i,s-1){
    REP(j,i,s) if(mat[j][i].val != 0) break;
    if(j!=i) rep(k,s) swap(mat[i][k], mat[j][k]);
    REP(j,i+1,s){
      t = mat[j][i] / mat[i][i];
      if(t.val==0) continue;
      REP(k,i,s){
//        printf("%d %d : %d -> ",j,k,(int)mat[j][k]);
        mat[j][k] -= mat[i][k] * t;
//        printf("%d\n",(int)mat[j][k]);
      }
    }
  }
//  rep(i,N){ rep(j,N) printf("%d ",(int)mat[i][j]); puts(""); } puts("");
  rep(i,s) res *= mat[i][i];

  if(cnt==0){
    k = N*N - M;
    res *= mint(k);
  }

  writerLn((int)res);

  return 0;
}