#include<fstream>
#define MOD 1000003
using namespace std;
int n,m,nr[100100];
bool viz[100100];

int main()
{
	int i,x;
	ifstream fin("grigo.in");
	fin>>n>>m;
	for(i=1;i<=m;i++)
	{
		fin>>x;
		viz[x]=true;
	}
	
	nr[1]=1;
	for(i=2;i<=n;i++)
	{
		if(viz[i])
			nr[i]=nr[i-1];
		else
			nr[i]=(1LL*(i-1)*nr[i-1])%MOD;
	}
	
	ofstream fout("grigo.out");
	fout<<nr[n]<<"\n";
	fout.close();
	return 0;
}