function sortStack(stack){
  var sortedStack = new Stack ();

  while (!stack.isEmpty()){

    var curr = stack.pop();

    while (!sortedStack.isEmpty() && sortedStack.peek().data > curr.data){
      stack.push(sortedStack.pop().data);
    }
    sortedStack.push(curr.data);

  }

  while (!sortedStack.isEmpty()){
    stack.push(sortedStack.pop().data);
  }

}