using System;
using System.IO;
using System.Linq;
using System.Collections;
using System.Collections.Generic;
using System.Numerics;
using System.Diagnostics;
using System.Text;
using System.Text.RegularExpressions;
using System.Threading.Tasks;
using static System.Math;
using static System.Console;

namespace yukicoder
{
    class Program
    {
        static void Main()
        {
            int N = int.Parse(Console.ReadLine());
            int K = int.Parse(Console.ReadLine());
            int[] nums = new int[K];
            

            for (int i = 0; i < K; i++)
            {
                nums[i] = int.Parse(Console.ReadLine());
            }

            int Min = nums.Min();
            int Max = nums.Max();

            Console.WriteLine(Max - Min);

        }
    }
}