Contraseña final, C#

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//Rextester.Program.Main is the entry point for your code. Don't change it.
//Compiler version 4.0.30319.17929 for Microsoft (R) .NET Framework 4.5

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;

namespace Rextester
{
    public class Program
    {
        public static void Main(string[] args)
        {
            //Your code goes here
            Console.WriteLine("Generador de contraseña");
            Random r=new Random();
            int a;
            Console.WriteLine();
            Console.Write("La nueva contraseña es: ");
            for (int cont=0; cont<=9;cont++)
            {
                a=r.Next(0,16);
                if(a<=9)
                {
                    Console.Write(a);
                }
                if(a==10)
                {
                    Console.Write("A");
                } 
                if(a==11)
                {
                    Console.Write("B");
                } 
                if(a==12)
                {
                    Console.Write("C");
                } 
                if(a==13)
                {
                    Console.Write("D");
                }
                if(a==14)
                {
                    Console.Write("E");
                }
                if(a==15)
                {
                    Console.Write("F");
                }
            }   
        }
    }
}

Show compiler warnings [ + ] Show input
Compilation time: 0,12 sec, absolute running time: 0,08 sec, cpu time: 0,09 sec, average memory usage: 14 Mb, average nr of threads: 3