#include <bits/stdc++.h>

using namespace std;

#define int long long
#define fir first
#define sec second
#define mkp make_pair 
#define pb push_back
#define lep( i, l, r ) for ( int i = ( l ); i <= ( r ); ++ i )
#define rep( i, r, l ) for ( int i = ( r ); i >= ( l ); -- i )

typedef long long ll;
typedef long double ld;
typedef pair < int, int > pii;

char _c; bool _f; template < class type > inline void read ( type &x ) {
	_f = 0, x = 0;
	while ( _c = getchar (), !isdigit ( _c ) ) if ( _c == '-' ) _f = 1;
	while ( isdigit ( _c ) ) x = x * 10 + _c - '0', _c = getchar (); if ( _f ) { x = -x; }
}

template < class type > inline void chkmin ( type &x, type y ) { x = ( x <= y ? x : y ); }
template < class type > inline void chkmax ( type &x, type y ) { x = ( x >= y ? x : y ); }

const int N = 1e6 + 5;
const int mod = 1e9 + 7;

int n, m, ans = 1;
int a[N], fac[N];

void init () {
  fac[0] = 1;
  for ( int i = 1; i <= n; i ++ ) {
    fac[i] = fac[i - 1] * i;
    fac[i] %= mod;
  }
}

int fast_pow ( int a, int b ) {
  int res = 1;
  while ( b ) {
    if ( b & 1 ) {
      res = res * a;
      res %= mod;
    }
    b >>= 1;
    a = a * a;
    a %= mod;
  }
  return res;
}

int C ( int n, int m ) {
  if ( n < m ) {
    return 0;
  }
  return fac[n] * fast_pow ( fac[m], mod - 2 ) % mod * fast_pow ( fac[n - m], mod - 2 ) % mod;
}

void Solve () {
  cin >> n >> m;
  for ( int i = 1; i <= m; i ++ ) {
    cin >> a[i];
  }
  init ();
  sort ( a + 1, a + 1 + m, [] ( int x, int y ) { return x > y; } );
  int block = n / m, res = 0;
  for ( int i = 1; i <= m; i ++ ) {
    ans *= C ( n - a[i] - res, block - 1 ) % mod;
    ans %= mod;
    // cout << C ( n - a[i] - res, block - 1 ) << '\n';
    res += block;
  }
  cout << ans;
}

signed main () {
#ifdef judge
  freopen ( "Code.in", "r", stdin );
  freopen ( "Code.out", "w", stdout );
  freopen ( "Code.err", "w", stderr );
#endif
  Solve ();
  return 0;
}