нужно написать экзамен по паскалю

const nMax=100; W=10;
type
  TBook = record
    Title, Author: String[127];
    Pages: Integer;
    Price: Real;
  end;
  TBooks = array [0..nMax-1] of TBook;
 
procedure ShellSort(var v: TBooks; n: Integer);
var
  gap, lt, rt, i: Integer;
  t: TBook;
begin
  gap:=1; while gap<n do gap:=3*gap+1; gap:=gap div 3;
  while gap>0 do begin
    for i:=0 to n-1-gap do begin
      lt:=i; rt:=lt+gap; t:=v[rt];
      while (lt>=0) and (v[lt].Price>t.Price) do begin
        v[rt]:=v[lt]; rt:=lt; Dec(lt,gap);
      end;
      v[rt]:=t;
    end;
    gap:=gap div 3;
  end;
end;
var
  Books: TBooks;
  BooksCnt, i: Integer;
  Sum: Real;
  f: Text;
begin
  Assign(f,'knihy.txt'); Rewrite(f);
  repeat
    Write('Books count [1..',nMax,']: '); ReadLn(BooksCnt);
  until (BooksCnt>0) and (BooksCnt<=nMax);
  WriteLn(f,BooksCnt); {Sum:=0;}
  for i:=0 to BooksCnt-1 do with Books[i] do begin
    WriteLn('Book # ',i);
    Write('Title: ':W);  ReadLn(Title);  WriteLn(f,Title);
    Write('Author: ':W); ReadLn(Author); WriteLn(f,Author);
    Write('Pages: ':W);  ReadLn(Pages);  WriteLn(f,Pages);
    Write('Price: ':W);  ReadLn(Price);  WriteLn(f,Price:0:2); WriteLn(f);
    Sum:=Sum+Price;
  end;
  WriteLn(  'Avg price: ',Sum/BooksCnt:0:2); WriteLn;
  WriteLn(f,'Avg price: ',Sum/BooksCnt:0:2); WriteLn(f);
  ShellSort(Books,BooksCnt);
  for i:=0 to BooksCnt-1 do with Books[i] do begin
    WriteLn(Title);  WriteLn(f,Title);
    WriteLn(Author); WriteLn(f,Author);
    WriteLn(Pages);  WriteLn(f,Pages);
    WriteLn(Price:0:2);  WriteLn(f,Price:0:2);
    WriteLn; WriteLn(f);
  end;
  Close(f);
end.