using System;

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Hello World");

        var dni = "62134854";

        var dig = "5";

        var xx = dni+dig;

        var yy = ValidaDNI_Peru(xx);

        Console.WriteLine(yy);

    }

    public static bool ValidaDNI_Peru(string dniAValidar)

    {

        if (!string.IsNullOrEmpty(dniAValidar))

        {

            int length = dniAValidar.Length;

            if (length != 9)

            {

                return false;

            }

​

            int num = 0;

            int[] array = new int[10] { 5, 4, 3, 2, 7, 6, 5, 4, 3, 2 };

            string text = dniAValidar.Substring(0, length - 1);

            int length2 = text.Length;

            int num2 = array.Length - length2;

            for (int num3 = length2 - 1; num3 >= 0; num3--)

            {

                num += (text[num3] - 48) * array[num3 + num2];

            }

​

            num = 11 - num % 11;

            if (num == 11)

            {

                num = 0;

            }

​

            char c = char.ToUpperInvariant(dniAValidar[length - 1]);

            if (length == 11)

            {

                return num.Equals(c - 48);

            }

​

            if (char.IsDigit(c))

            {

                char[] array2 = new char[11]

                {

                    '6', '7', '8', '9', '0', '1', '1', '2', '3', '4',

                    '5'

                };

                return c.Equals(array2[num]);

            }

​

            if (char.IsLetter(c))

            {

                char[] array3 = new char[11]

                {

                    'K', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I',

                    'J'

                };

                return c.Equals(array3[num]);

            }

        }

​

        return false;

    }

​

}