# include <stdio.h>

# define FIN "grigo.in"
# define FOUT "grigo.out"
# define MAXN 100001
# define INF 1000003

unsigned char s[MAXN];
long long N,M,i;
long long aux;

    int main()
    {
        freopen(FIN,"r",stdin);
        freopen(FOUT,"w",stdout);
        
        scanf("%lld%lld",&N,&M);
        long x;
        for (i = 1; i <= M; ++i)
          {
              scanf("%lld",&x);
              s[x]=1;
          }
        aux=1;
        for (i = 2; i <= N; ++i)
          if (s[i]==0) aux=((i-1)*aux)%INF;
          
        printf("%lld",aux);
        
        return 0;
    }