using System;
using System.Linq;

class Program
{
    static void Main()
    {
        var _ = Console.ReadLine();
        var iter =
            from x in Console.ReadLine().Trim().Split(' ')
            select int.Parse(x);
        var r = (int) Math.Sqrt(iter.Sum());
        
        var cnt = 0;
        var flg = true;
        var h = 1;

        foreach (var a in iter)
        {
            if (a > h)
            {
                cnt += a - h;
            }
            if (flg)
            {
                ++h;
                
                if (h >= r)
                {
                    flg = false;
                }
            }
            else if (h > 0)
            {
                --h;
            }
        }

        Console.WriteLine(cnt);
    }
}