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

public class Main {

    public static void main(String[] args) {
        AReader scanner = new AReader();
        int res = 0;
        String s;
        while (scanner.hasNext()) {
            s = scanner.next();
            if ("0".equals(s)) {
                break;
            }
            res += (s.length() - s.replaceAll("bug", "").length()) / 3;
        }
        System.out.println(res);
    }
}

class AReader {
    private BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
    private StringTokenizer tokenizer = new StringTokenizer("");

    private String innerNextLine() {
        try {
            return reader.readLine();
        } catch (IOException ex) {
            return null;
        }
    }

    public boolean hasNext() {
        while (!tokenizer.hasMoreTokens()) {
            String nextLine = innerNextLine();
            if (nextLine == null) {
                return false;
            }
            tokenizer = new StringTokenizer(nextLine);
        }
        return true;
    }

    public String nextLine() {
        tokenizer = new StringTokenizer("");
        return innerNextLine();
    }

    public String next() {
        hasNext();
        return tokenizer.nextToken();
    }

    public int nextInt() {
        return Integer.parseInt(next());
    }
}