using System.IO;

namespace ttt
{
    internal class Program
    {
        static void Main(string[] args)
        {
            int max = 50;

            int n = int.Parse(Console.ReadLine());
            string input = Console.ReadLine();
            int[] nums = input.Split(' ').Select(int.Parse).ToArray();
            int[] count = new int[max + 1];
            int total = 0;

            foreach (int i in nums)
                count[i]++;

            for (int i = max; i > 0; i--)
                while (count[i] > 1)
                {
                    for (int j = i + 1; j <= max; j++)
                        if (count[j] == 0)
                        {
                            count[j] = 1;
                            count[i]--;
                            total++;
                            break;
                        }
                }

            Console.WriteLine(total);
        }
    }
}