#include <bits/stdc++.h>

using namespace std;

const long long max_size = 1e5 + 1, mod = 1e6 + 3;

long long v[max_size];

signed main ()
{
    #ifdef LOCAL
       freopen("test.in", "r", stdin);
       freopen("test.out", "w", stdout);
    #else
       freopen("grigo.in", "r", stdin);
       freopen("grigo.out", "w", stdout);
    #endif // LOCAL
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    long long n, k;
    cin >> n >> k;
    for (long long i = 1; i <= k; i++)
    {
        long long x;
        cin >> x;
        v[x - 1] = 1;
    }
    long long ans = 1;
    for (long long i = 1; i < n; i++)
    {
        if (v[i] == 0)
        {
            ans = (ans * i) % mod;
        }
    }
    cout << ans;
    return 0;
}