program broask_dilie;
const ct=1000003;
var v:array[1..100000]of boolean;
    m,n,i,x:longint;
    p:int64;
    f:text;
begin
assign(f,'grigo.in');reset(f);
readln(f,n,m);
for i:=1 to m do begin
    read(f,x);v[x]:=true;
    end;
close(f);p:=1;
for i:=2 to n do if not v[i] then p:=p*(i-1)mod ct;
assign(f,'grigo.out');rewrite(f);write(f,p);close(f);
end.