throw probability simulation, C#

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//Rextester.Program.Main is the entry point for your code. Don't change it.
//Microsoft (R) Visual C# Compiler version 2.9.0.63208 (958f2354)

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

namespace Rextester
{
    public class Program
    {
        public static Random rnd = new Random();
        public static void Main(string[] args)
        {
            Dictionary<int, int> successes = new Dictionary<int, int>();
            Dictionary<int, int> failures = new Dictionary<int, int>();
            for (int testVal = 2; testVal <= 37; testVal++)
            {
                for (int a = 0; a < 100000; a++) {
                    int result = doRoll(testVal);
                    if (result > 0) {
                        if (!successes.ContainsKey(testVal)) {
                            successes.Add(testVal, 0);
                        }
                        successes[testVal]++;
                    }
                    else {
                        if (!failures.ContainsKey(testVal)) {
                            failures.Add(testVal, 0);
                        }
                        failures[testVal]++;
                    }
                }
                double successrate = successes[testVal] / 100000.0 * 100.0;
                successrate = Math.Truncate(successrate * 100) / 100;
                double failrate = 100.00 - successrate;
                failrate = Math.Truncate(failrate * 100) / 100;
                Console.WriteLine("Agility " + testVal + ":  " + successrate.ToString(new CultureInfo("en-US")) + "% successful, " + failrate.ToString(new CultureInfo("en-US")) + "% failing.");
            }
        }
        public static int doRoll(int agility)
        {
            string Dice = "1d" + agility;
            char[] splitterD = new char[1]
            {
                'd'
            };
            string[] array5 = Dice.Split(splitterD, 2);
			int number_1 = Convert.ToInt32(array5[0]);
			int number_Agi = Convert.ToInt32(array5[1]);
            int penCount = 0;
            string info = "";
            for (int i = 0; i < number_1; i++)
            {
                int rollTotal = 0;
                int rand_1_to_Agi = 0;
                bool flag = true;
                do
                {
                    rand_1_to_Agi = rnd.Next( 1, number_Agi + 1);
                    info += " [" + rand_1_to_Agi + "]";
                    rollTotal += rand_1_to_Agi;
                    if (flag)
                    {
                        flag = false;
                    }
                    else
                    {
                        rollTotal--;
                    }
                    if (rollTotal * 1 + 0 >= 3)
                    {
                        penCount++;
                        break;
                    }
                }
                while (rand_1_to_Agi == number_Agi);
                info += " {" + rollTotal + "}";
            }
            //Console.WriteLine(penCount + info);
            return penCount;
        }
    }
}

Show compiler warnings [ + ] Show input
Compilation time: 0,56 sec, absolute running time: 4,94 sec, cpu time: 4,94 sec, average memory usage: 35 Mb, average nr of threads: 5, absolute service time: 5,52 sec