求助（20分）

为什么只有20分？！

var a,b,c:array[1..1000] of longint;
    n1,n2:string;
    l1,l2,l3,x,i,j:longint;
    begin
    readln(n1);
    readln(n2);
    if (n1[1]='-')and(n2[1]='-') then begin
    delete(n1,1,1);
    delete(n2,1,1);
    end
    else if(n1[1]='-')or(n2[1]='-') then begin
    write('-');
    if n1[1]='-' then delete(n1,1,1);
    if n2[1]='-' then delete(n2,1,1);
    end;
    l1:=length(n1);
    l2:=length(n2);
    for i:=1 to l1 do a[l1-i+1]:=ord(n1[i])-48;
    for i:=1 to l2 do b[l2-i+1]:=ord(n1[i])-48;
    for i:=1 to l1 do
    begin
    x:=0;
    for j:=1 to l2 do
    begin
    c[i+j-1]:=c[i+j-1]+a[i]*b[j]+x;
    x:=c[i+j-1] div 10;
    c[i+j-1]:=c[i+j-1] mod 10;
    end;
    c[i+j]:=x;
    end;
    l3:=l1+l2;
    while (c[l3]=0)and(l3>1) do dec(l3);
    for i:=l3 downto 1 do
    write(c[i]);
end.