var
  n,i,j,sum:longint;
  a,b:array[0..5000] of longint;
procedure pk(l,r:longint);
  var i,j,mid:longint;
  begin
   i:=l;j:=r;mid:=a[(l+r) div 2];
   repeat
    while a[i]<mid do inc(i);
    while a[j]>mid do dec(j);
    if i<=j then
     begin
      a[0]:=a[i];a[i]:=a[j];a[j]:=a[0];
      b[0]:=b[i];b[i]:=b[j];b[j]:=b[0];
      inc(i);dec(j);
       end;
    until i>j;
    if l<j then pk(l,j);
    if i<r then pk(i,r);
   end;
begin
  readln(n);
  for i:=1 to n do begin read(a[i]);b[i]:=i;end; 
   pk(1,n);
    for i:=1 to n do write(b[i],' ');writeln;
    for i:=1 to n do
     sum:=sum+a[i]*(n-i);
    write(sum/n:0:2);
end.

哪位大佬知道错哪？？