using System;
using System.Text;
using System.Linq;
using System.Collections.Generic;
using System.Reflection;
        
public class Program
{
public static void Main(string[] args)
{
    string test = "ABC";
    Type t = test.GetType();
    var indexer = t.GetProperties()
        .Where(p => p.GetIndexParameters().Length != 0)
        .FirstOrDefault();
    if (indexer != null)
    {
        object[] indexArgs = { 1 };
        var secondChar = indexer.GetValue(test, indexArgs);
        Console.Write(secondChar);
    }
}
}