import java.util.Scanner;
import java.util.ArrayList;
import java.util.List;

class Main {
    public static void main(String[] args) throws Exception {
        Scanner in = new Scanner(System.in);
        String s = in.nextLine();
        int n = s.length();

        List<String> str = new ArrayList<String>();
        List<Integer> len = new ArrayList<Integer>();

        int max = 0;
        int i = 0;
        while(i < n) {
            int j = s.indexOf('w', i);
            if(j == -1) {
                break;
            } else if(j == 0) {
            } else {
                str.add(s.substring(i, j));
                i = j;
            }

            int temp = 0;
            while(i < n && s.charAt(i) == 'w') {
                temp++;
                i++;
            }
            if(j > 0) {
                len.add(temp);
                max = Math.max(max, temp);
            }
        }

        if(str.size() == 0) {
            System.out.println();
        } else {
            for(int j=0; j<str.size(); j++) {
                if(len.get(j) == max) {
                    System.out.println(str.get(j));
                }
            }
        }
    }
}