1. var CQueue = function () {
    2.   this.stack1 = []
    3.   this.stack2 = []
    4. };
    6. /** 
    7.  * @param {number} value
    8.  * @return {void}
    9.  */
    10. CQueue.prototype.appendTail = function (value) {
    11.   this.stack1.push(value)
    12. };
    14. /**
    15.  * @return {number}
    16.  */
    17. CQueue.prototype.deleteHead = function () {
    18.   if (this.stack2.length) {
    19.     return this.stack2.pop()
    20.   } else if (this.stack1.length) {
    21.     while (this.stack1.length) {
    22.       this.stack2.push(this.stack1.pop())
    23.     }
    24.     return this.stack2.pop()
    25.   }
    26.   return -1;
    27. };
    29. /**
    30.  * Your CQueue object will be instantiated and called as such:
    31.  * var obj = new CQueue()
    32.  * obj.appendTail(value)
    33.  * var param_2 = obj.deleteHead()
    34.  */