using System;
using System.Linq;

class Program77
{
    private static int PyramidCount(int row)
    {
        int sum = 0;
        for (int i = 1; i < (row+1)/2; i++)
        {
            sum += i*2;
        }
        sum += (row + 1) / 2;
        return sum;
    }

    public static void Main(string[] args)
    {
        int n = int.Parse(Console.ReadLine());
        var values = Console.ReadLine().Split(' ').Select(int.Parse).ToArray();
        var sum = values.Sum();
        int row = -1;
        while (true)
        {
            int count = PyramidCount(row+2);
            if (count > sum)
            {
                break;
            }
            row += 2;
        }
        int minValue = int.MaxValue;
        for (int currentRow = 1; currentRow <= row; currentRow+=2)
        {
            var upper = Math.Max(values.Length, currentRow+1);
            int diff = sum - PyramidCount(currentRow);
            int move = 0;
            for (int index = 0; index < upper; index++)
            {
                var center = (currentRow + 1) / 2;
                int height = center - Math.Abs(center - (index + 1));
                if (currentRow <= index)
                {
                    move += height;
                }
                else
                {
                    move += Math.Abs(values[index] - height);
                }
            }
            var count = (move - diff)/2;
            minValue = Math.Min(minValue, Math.Abs(count));
        }
        Console.WriteLine(minValue);
    }
}