Can we put simultanously Two symbols in stack in one of the video on youtube it is showing that we can put two a's on to the stack I'm not finding it correct plzz calrify my doubt it on place of one a we are putting two a's one extra a is also there what about that because any how 1 b is poping out 1 a then no.of b's will be fine but what about one extra which has been take out