#include <bits/stdc++.h>

using namespace std;
int vc[100001],dp[100001];
#define mod 1000003

int main()
{
    ifstream cin("grigo.in");
    ofstream cout("grigo.out");

    int n,m,i,a;
    cin>>n>>m;
    for(i=1;i<=m;++i){
        cin>>a;
        vc[a]=1;
    }
    dp[1]=1;
    for(i=2;i<=n;++i){
        if(vc[i]==0)
            dp[i]=(1LL*dp[i-1]*(i-1))%mod;
        else
            dp[i]=dp[i-1];
    }
    cout<<dp[n];
    return 0;
}