using System;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Nhap so phan tu X");

        int x = int.Parse(Console.ReadLine());

        GenerateRandomString(x);

    }

     static string GenerateRandomString(int x)

{

    char[] characters = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789".ToCharArray();

    Random random = new Random();

    List<char> result = new List<char>();

​

    for (int i = 0; i < x; i++)

    {

        result.Add(characters[random.Next(characters.Length)]);

    }

​

    return new string(result.ToArray());

}

}