// make list

cell[1000]; freecell;

// access functions
head(a){  return cell[a];}
tail(a){  return cell[a+1];}
sethead(a,i){  cell[a] = i;}
settail(a,i){  cell[a+1] = i;}

newnode(i){    // get a new node, with i
  p = freecell;
  freecell = freecell + 2;
  if( freecell > 10000 ) print("no more cell");
  sethead(p,i);
  settail(p,0);
  return p;
}

// link node a to list m
insert(m,a){ 
  settail(a,tail(m));
  settail(m,a);
}

// print item in list recursively
prlist2(m){
  if( m != 0 ){
    print(head(m)," ");
    prlist2(tail(m));
  }
}

// main print list, skip header node
prlist(m){ prlist2(tail(m)); }

main(){
  h = newnode(0);       // make header
  insert(h,newnode(1));
  insert(h,newnode(2));
  insert(h,newnode(3));
  prlist(h);
}