using System;

using System.Text.RegularExpressions;

​

public class Program

{

    public static void Main()

    {

        string input = "ab";

​

        Match m1 = Regex.Match(input, "a(){2,}?b");

        Match m2 = Regex.Match(input, "a(){100,}?b");

​

​

        Console.WriteLine($"{m1.Success} {m1.Value}");

        Console.WriteLine($"{m2.Success} {m2.Value}");

    }

}

​