On my computer it is working correctly.

var a : array [1..100, 1..100] of integer;
result : array [1..20000] of integer;
i, j, ah, b, n, count : integer;
begin
  readln (n);
  for i := 1 to n do begin
    for j := 1 to n do
      read (a[i, j]);
    readln;
  end;
  for i := 1 to (n*2-1) do begin
    if (i < n) then begin
      ah := i;
      b := 1;
    end else begin
      ah := n;
      b :=  i - n + 1;
    end;
    while (ah>=1) do begin
      inc (count);
      result [count] := a [ah, b];
      dec (ah);
      inc (b);
    end;
  end;
  for i := 1 to count do
    if (result [i] <> 0) then
      write (result [i]);
  writeln;
end.

I think u should write " " after each number