import java.util.*;

public class Main {
    static Scanner scanner = new Scanner(System.in);

    public static void main(String[]$) {
        char[] s = scanner.next().toCharArray();
        List<String> list = new ArrayList<>();
        for (int i = s.length - 1, c = 0; i >= 0; i--) {
            if (s[i] == 'B') {
                c++;
            } else if (0 < c) {
                c--;
            } else {
                list.add(0, String.valueOf(s[i]));
            }
        }
        System.out.println(String.join("", list));
    }
}
/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz