Detect HTML Tags

import java.util.HashSet;
import java.util.Scanner;
import java.util.Set;
import java.util.TreeSet;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class Solution{


	public static void main(String[] args) {
		/* Enter your code here. Read input from STDIN. Print output to STDOUT. Your class should be named Solution. */
		
		Scanner in = new Scanner(System.in);
		int n = Integer.parseInt(in.nextLine());
		String string;
		String regexOnlyTag = "[<][^>]+";
		String regexATag = "[\\[]";
		Pattern tagPattern = Pattern.compile(regexOnlyTag);
		Set<String> tagSet = new HashSet<String>();
		for (int i = 0; i < n; i++)
		{
			string = in.nextLine();
			Matcher tagMatcher = tagPattern.matcher(string);
			while(tagMatcher.find())
			{
				String temp = string.substring(tagMatcher.start(), tagMatcher.end());
				temp = temp.trim();
				temp = temp.replaceAll("[<|>|/]", "");
				String[] temparr = temp.split(" ");
				String tempNew = temparr[0].trim();
				tagSet.add(tempNew);
			}
			if(string.contains("["))
				tagSet.add("a");
		}
		// sort the map based on key field
		Set<String> sortedSet = new TreeSet<String>(tagSet);
		StringBuffer strbuff = new StringBuffer();
		for(String item : sortedSet)
			strbuff.append(item + ";");
		strbuff.deleteCharAt(strbuff.length() - 1);
		System.out.println(strbuff.toString());
		
	}
}