#include <cstdio>
const int p=1000003;
bool u[100001];
long long sol;
int main(){
    int i,j,n,m;
    freopen("grigo.in","r",stdin);
    freopen("grigo.out","w",stdout);
    scanf("%d %d",&n,&m);
    for (i=1;i<=m;++i) 
      scanf("%d",&j),u[j]=true;
    for (sol=1,i=2;i<=n;++i)
     if (!u[i]) sol=(sol*(i-1))%p;
    printf("%lld",sol);
    return 0;
}