using System;

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Hello World");

        //{1,1,1,1,1} -->5

        //{1,7,5,2,9} --> {9,7,5,2,1} --> 1 rom for 9,7,5. one room for 2 . one room for 1 -->

        int[] guests=new int[] {7,3,1,1,4,5,4,9};//{2,7,2,9,8};//{2,1,4};//{1,1,1,1,1};//{1,7,5,2,9};

        Console.WriteLine(NumberOfRooms(guests).ToString());

    }

    public static int NumberOfRooms(int[] guests)

    {

        //Array.Sort<>(guests);

        Array.Sort(guests);

        int rooms=1;//guests.Length;

        Console.WriteLine(guests.Length.ToString());

        int persons=0;

        if((guests[0]==guests[guests.Length-1]) && guests[0]==1) return guests.Length;

        for(int i=guests.Length-1;i>=0;i--)

        {

            Console.WriteLine(i.ToString());

            if(guests[i]>1 && persons<=guests[i]){

                persons++;

                //rooms--;

            }   

            else

            {

                rooms++;

                persons=0;

            }

        }

        return rooms;

    }

}