var StackedStacks = function(){
  this.stackArray = [];
  this.maxSize = 2;
}

StackedStacks.prototype.push = function (data){

  var stackIndex = this.stackArray.length - 1;
  var currStack = this.stackArray[stackIndex];

  if (stackIndex == -1 || (currStack.size >= this.maxSize)){
    var stack = new Stack();
    stack.push(data);
    this.stackArray.push(stack);
  }
  else{
    currStack.push(data);
    this.stackArray[stackIndex] = currStack;
  }

}