/**
PLEASE
COPY AND PASTE MY CODE
[I AM SARCASTIC]
**/
#include <fstream>
using namespace std;
ifstream Q("grigo.in");
ofstream W("grigo.out");
long long n,v[100005],k,r;
int main()
{
    Q>>n>>k;
    for(int i=1;i<=k;i++)
        Q>>r,v[r-1]=1;
    r=1;
    for(int i=1;i<n;i++)
        if(!v[i])
            r=r*i*1ll%1000003;
    W<<r;
    return 0;
}