#include <iostream>
#include <fstream>

using namespace std;

const int mod = 1000003;

int N, M, sol = 1;
char viz[100005];

int main()
{
    ifstream f("grigo.in");
    ofstream g("grigo.out");

    f >> N >> M;

    for ( int i = 1, a; i <= M; ++i )
    {
        f >> a;
        viz[a] = 1;
    }

    for ( int i = 1; i <= N; ++i )
            if ( viz[i] == 0 )
                    sol = ( ( i - 1 ) * sol ) % mod;

    g << sol << "\n";

    f.close();
    g.close();

    return 0;
}