#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;
}