It seems to me that the effect of SSS on the first staircase is much easier to make than it is to cause the effect of the staircase located below. Good Demo
@Denis Nazin ..i am not sure I understand what you meant but is it the same as i thought, that the lower step set at 90 degrees to the overlying step would normally prevent the SSS fro working but seems to have no effect in this level.
In this level, SSS is only blocked if the lower stair is rotated 180° - facing the other way round. Because when B does SSS, he ignores the stair on top and only sees the block that is underneath that stair. In this case, it's possible for B to proceed as the stair are in correct configuration. If it's a grass block underneath the stair, then B can go all direction - left, right(SSS) and forward(SBS)