Вычислить произведение элементов по столбцам массива с[1..7,1..7] — Pascal(Паскаль)

const
  n = 7;

var
  a: array [1 .. n, 1 .. n] of integer;
  i, j, pr: integer;

begin
  for i := 1 to n do
  begin
    for j := 1 to n do
    begin
      a[i, j] := random(10);
      write('  ', a[i, j]:3);
    end;
    writeln();
  end;
  writeln('--------');

  for j := 1 to 7 do
  begin
    pr := 1;
    for i := 1 to 7 do
      if a[i, j] = 0 then
      begin
        pr := 0;
        break;
      end
      else
        pr := pr * a[i, j];
  end;
  writeln(pr, ' ');

  writeln('--------');

end.