#include <fstream>
using namespace std;
ifstream f("grigo.in"); ofstream g("grigo.out");
int n,m,x,i,nr=1;
bool ok[1000001];
int main ()
{   f>>n>>m;
    while(m--) f>>i, ok[i]=1;
    for(i=1;i<=n;++i)
        if(!ok[i]) nr=(1LL*(i - 1)*nr)%1000003;
    g<<nr<<'\n'; g.close(); return 0;
}