import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Comparator;
import java.util.InputMismatchException;
import java.util.NoSuchElementException;
import java.math.BigInteger;

public class Main{

    static PrintWriter out;
    static BufferedReader ir;

    static void solve() throws IOException{
		String s=ir.readLine();
		ArrayList<String> ans=new ArrayList<>();
		ans.add("");
		int l=0,ma=0;
		while(l<s.length()&&s.charAt(l)=='ｗ') l++;
		ma=l;
		for(int i=l;i<s.length();i++){
			if(s.charAt(i)=='ｗ'){
				int st=i;
				while(i<s.length()&&s.charAt(i)=='ｗ') i++;
				l=i;
				if(i-st+1>ma){
					ma=i-st+1;
					ans.clear();
					ans.add(s.substring(l,st));
				}
				else if(i-st+1==ma) ans.add(s.substring(l,st));
			}
		}
		for(String ss : ans){
			out.println(ss);
		}
	}

	public static void main(String[] args) throws Exception{
		ir=new BufferedReader(new InputStreamReader(System.in,"UTF-8"));
		out=new PrintWriter(System.out);
		solve();
		out.flush();
	}
}