text: /* The Great Computer Language Shootout
     http://shootout.alioth.debian.org/
     contributed by Isaac Gouy */
  
  function TreeNode(left,right,item){
     this.left = left;
     this.right = right;
     this.item = item;
  }
  
  TreeNode.prototype.itemCheck = function(){
     if (this.left==null) return this.item;
     else return this.item + this.left.itemCheck() - this.right.itemCheck();
  }
  
  function bottomUpTree(item,depth){
     if (depth>0){
        return new TreeNode(
            bottomUpTree(2*item-1, depth-1)
           ,bottomUpTree(2*item, depth-1)
           ,item
        );
     }
     else {
        return new TreeNode(null,null,item);
     }
  }
  
  var ret;
  
  for ( var n = 4; n <= 7; n += 1 ) {
      var minDepth = 4;
      var maxDepth = Math.max(minDepth + 2, n);
      var stretchDepth = maxDepth + 1;
      
      var check = bottomUpTree(0,stretchDepth).itemCheck();
      
      var longLivedTree = bottomUpTree(0,maxDepth);
      for (var depth=minDepth; depth<=maxDepth; depth+=2){
          var iterations = 1 << (maxDepth - depth + minDepth);
  
          check = 0;
          for (var i=1; i<=iterations; i++){
              check += bottomUpTree(i,depth).itemCheck();
              check += bottomUpTree(-i,depth).itemCheck();
          }
      }
  
      ret = longLivedTree.itemCheck();
  }
  