var a:array [1..100,1..100] of byte;
    i,j,n,x,y,k:byte;
begin
  readln(n);
  x:=1;
  a[1,n]:=x;
  inc(x);
  for j:=n-1 downto 1 do
    begin
      i:=1;
      k:=j;
      while k<=n do
        begin
          a[i,k]:=x;
          inc(x);
          inc(i);
          inc(k);
        end;
    end;
  for i:=2 to n do
    begin
      j:=1;
      k:=i;
      while k<=n do
        begin
          a[k,j]:=x;
          inc(x);
          inc(k);
          inc(j);
        end;
    end;
  for i:=1 to n do
    begin
      for j:=1 to n do
        write(a[i,j],' ');
      writeln;
    end;
  readln;
end.

Got it AC now.... Just changed from byte to integer.