var n,m,nr,i:longint;
    v:array[1..100000]of integer;
    r:int64;
begin
read(n,m);
 for i:=1 to m do begin
  read(nr);
  v[nr]:=1;
 end;
 for i:=1 to n do
  if v[i]=0 then r:=(r*(i-1))mod 1000003;
end.