30
x 1 t 1 x 1 t 1 t 1 x 1 x 1 x 1 x 1 x 1 x 1 t 1 t 1 x 1 t 1 x 1 x 1 t 1 x 1 x 1 t 1 x 1 x 1 x 1 x 1 x 1 t 1 x 1 x 1 x 1