using System;
using static System.Console;
using System.Linq;
using System.Collections.Generic;

class Program
{
    static int NN => int.Parse(ReadLine());
    static int[] NList => ReadLine().Split().Select(int.Parse).ToArray();
    public static void Main()
    {
        Solve();
    }
    static void Solve()
    {
        var c = NList;
        var (l, n) = (c[0], c[1]);
        var x = NList;
        var dp = new bool[l * 2 + 1];
        dp[x[0] + x[^1]] = true;
        for (var i = 1; i < x.Length; ++i)
        {
            var ndp = new bool[dp.Length];
            for (var j = 0; j < dp.Length; ++j)
            {
                var nj = j + x[i] - x[i - 1];
                if (nj >= 0 && nj < ndp.Length) ndp[nj] |= dp[j];
                nj = j - x[i] + x[i - 1];
                if (nj >= 0 && nj < ndp.Length) ndp[nj] |= dp[j];
            }
            dp = ndp;
        }
        for (var i = 0; i <= l; ++i)
        {
            if (dp[l + i] || dp[l - i])
            {
                WriteLine(i);
                return;
            }
        }
    }
}