program Snake; const n = 6; var Mas : array [1..n, 1..n] of Integer; k : Integer;
x, y : Integer; i : Integer;

begin WriteLn; WriteLn; i := 1;

for k := 1 to n do begin x := k; y := 1;

while x > 0 do
begin
  if ((x+y) mod 2=0) then begin
    Mas[y, x] := i;
  end
  else begin
    Mas[x, y] := i;
  end;

  i := i + 1;
  x := x - 1; 
  y := y + 1  
end

end;

for k := 2 to n do begin x := n; y := k;

while y <= n do
begin
  if((x+y)mod 2=0) then begin
    Mas[y, x] := i;
  end
  else begin
    Mas[x, y] := i;
  end;

  i := i + 1;
  x := x - 1; 
  y := y + 1  
end

end;

for y := 1 to n do begin

for x := 1 to n do
  Write(Mas[x, y] : 4);

WriteLn

end end.