using System;

class OverflowException: Exception {}
class UnderflowException: Exception {}

// generic queue
struct Queue {
  object[] values;
  int size, head, tail;
  
  public Queue(int size) {
    this.size = size;
    values = new object[size];
    head = tail = 0;
  }
  
  public void Enqueue(object x) {
    int tail1 = (tail + 1) % size;
    if (tail1 == head) throw new OverflowException();
    values[tail] = x;
    tail = tail1;
  }
  
  public object Dequeue() {
    if (head == tail) throw new UnderflowException();
    object x = values[head];
    head = (head + 1) % size;
    return x;
  }
  
  public int Length() {
    return (tail + 10 - head) % size;
  }
}

// program that uses a queue to store integers and strings
class Test {
  
  public static void Main() {
    Queue q = new Queue(10);
    
    q.Enqueue(1); q.Enqueue(2); q.Enqueue(3);
    while (q.Length() > 0) {
      Console.Write((int)q.Dequeue() + " ");
    }
    Console.WriteLine();
    
    q.Enqueue("Alice"); q.Enqueue("Bob"); q.Enqueue("Charly");
    while (q.Length() > 0) {
      Console.Write((string)q.Dequeue() + " ");
    }
    Console.WriteLine();
  }
}