using System;

using System.Linq;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        //Console.WriteLine("Hello World");

        var newWave = wave("Don't do drugs");

    }

    public static List<string> wave(string str)

    {

        var result = new List<string> {};

        //if(string.IsNullOrWhiteSpace(str)) return result;

​

        for(int i = 0; i < str.Length; i++)

        {

            var str1 = str.Substring(0,i);

            //Console.WriteLine(str1);

            var upper = str.Substring(i,1).ToUpper();

            var str2 = str.Substring(i+1);

            if(string.IsNullOrWhiteSpace(upper)) continue;

            result.Add(str1+upper+str2);

        }

​

        foreach(var r in result)

        {

            Console.WriteLine(r);

        }

        return result;

    }

}