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

namespace _5.ChangeTextInTheTags
{
    class ChangeTextInTheTags
    {
        static void Main()
        {
            string str = "We are living in a <upcase>yellow submarine</upcase>. We don't have <upcase>anything</upcase> else.";
            string searchedPattern = "</";
            string newString = str.Replace(searchedPattern, "");
            int numberOfTags = (str.Length - newString.Length) / searchedPattern.Length;
            int startSearchIndex = 0;
            for (int i = 0; i < numberOfTags; i++)
            {
                int startTagEndIndex = str.IndexOf(">",startSearchIndex);
                int endTagStartIndex = str.IndexOf("</", startTagEndIndex);
                string betweenTags = str.Substring(startTagEndIndex + 1, endTagStartIndex - startTagEndIndex - 1);
                str = str.Remove(startTagEndIndex + 1,endTagStartIndex - startTagEndIndex - 1);
                str = str.Insert(startTagEndIndex+1,betweenTags.ToUpper());
                int endTagEndIndex = str.IndexOf(">", endTagStartIndex);
                startSearchIndex = endTagEndIndex + 1;
            }
            Console.WriteLine(str);
        }
    }
}