: stack ( n"-  ) create 0 , allot ;
: push  ( na-  ) dup ++ dup @ + ! ;
: pop   (  a-n ) dup @ over -- + @ ;
: top   (  a-n ) dup @ + @ ;
: empty? ( a-f ) @ 0 = ;

10 stack st

1 st push
2 st push
3 st push
st empty? putn
st top putn
st pop putn st pop putn st pop putn
st empty? putn