import java.io.*;
import java.util.*;

public class SmallPath {

	public static void main(String args[]) throws Exception {

		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		PrintWriter pw = new PrintWriter(new BufferedWriter(new OutputStreamWriter(System.out)));
		
		String[] tags = br.readLine().split("!");		
		Stack<Pair<String>> sol = new Stack<>();
		
		for(int i = 0; i < tags.length; i++) {
			String tag = tags[i];
			
			if(sol.isEmpty())
				sol.push(new Pair<String>("", tag));
			else if(sol.peek().first.toLowerCase().compareTo(tag.toLowerCase()) == 0)
				sol.pop();
			else if(i == tags.length-1 || sol.peek().second.toLowerCase().compareTo(tag.toLowerCase()) != 0)
				sol.push(new Pair<String>(sol.peek().second, tag));		
		}
		
		String fin = sol.pop().second;
		
		while(!sol.empty()) 
			fin = sol.pop().second + "!" + fin;
		
		
		pw.println(fin);
		pw.close();
	}
	
	static class Pair<T>{
		T first, second;
		
		public Pair(T f, T s) {
			first = f;
			second = s;
		}
		
		@Override
		public String toString() {
			return first + " -> " + second;
		}
	}
}