Chiar daca am luat 100, atunci cand rulez programul ma scoate cu error 2, desi am fisierele adunare.in si adunare.out in acelasi loc cu programul. Care e problema?

Mersi, acum am 100 de puncte

Ce nu am facut bine?

Cod:

program adunare;
        var a,b,S:longint;
        adunin,adunout:text;
begin
        assign(adunin,'adunare.in');
        assign(adunout,'adunare.out');
        reset(adunin);rewrite(adunout);
        readln(a,b);
        S:=a+b;
        if(S<=2000000000)then
        writeln(adunout,S);
        close(adunin);
        close(adunout);
end.