class CircularQueue {
    private var data: [Int]
    private var front, rear, size : Int

    init(size: Int){
        self.front = -1
        self.rear = -1
        self.size = size
        self.data = Array(repeating: 0, count: size)
    }

    func isEmpty() -> Bool {
        return self.front == -1
    }

    func isFull() -> Bool {
        return (self.rear + 1)%self.size == self.front
    }

    func info(){
        if self.isEmpty(){
            print("Empty!")
            return
        }
        var i: Int = self.front
        while true {
            print("\(self.data[i]) ",terminator: " ")
            if i == self.rear {
                print()
                break
            }
            i = (i+1)%self.size
        }
    }

    func enqueue(to value: Int){
        if self.isFull() {
            print("Full!!!")
            return
        }

        if self.isEmpty(){
            self.front = 0
        }
        self.rear = (self.rear + 1)%self.size
        self.data[self.rear] = value
    }

    func dequeue() -> Int? {
        if self.isEmpty(){
            return nil
        }
        let value: Int = self.data[self.front]
        if(self.front == self.rear){
            self.front = -1
            self.rear = -1
        }
        else {
            self.front = (self.front+1) % self.size
        }

        return value
    }

    func peek() -> Int? {
        if self.isEmpty(){
            return nil
        }
        return self.data[self.front]
    }
}

let cirQueue: CircularQueue = CircularQueue(size: 10)
var exitFlag: Bool = true

while exitFlag {
    print("명령어를 입력하세요 (enqueue [값], dequeue, peek, info, exit):")
    if let input = readLine() {
        let components = input.split(separator: " ")
        let order = String(components.first ?? "")

        switch order {
            case "enqueue" :
                if components.count == 2, let value = Int(components[1]) {
                    cirQueue.enqueue(to: value)
                    print("\(value) enqueue!")
                }
                else {
                    print("enqueue 명령어 뒤에 공백에 이어서 숫자를 입력해야합니다.")
                }
            case "dequeue" :
                if let value = cirQueue.dequeue(){
                    print("\(value) dequeue!!")
                }
                else {
                    print("Empty!!")
                }
            case "peek" :
                if let value = cirQueue.peek(){
                    print("\(value) peek!!")
                }
                else {
                    print("Empty!!")
                }
            case "info" :
                cirQueue.info()
            case "exit" :
                exitFlag = false
                print("Exit!!!")
            default :
                print("제대로 된 명령어를 입력하세요")
        }
    }
    else {
        print("제대로 입력해주세요")
    }
}