import java.util.*;

public class CF0721a {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        long n = sc.nextInt();
        String[] s = sc.next().split("W+");

        ArrayList<Integer> ans = new ArrayList<>();
        for (String s_data : s) {
            if (!s_data.isEmpty()) {
                ans.add(s_data.length());
            }
        }

        System.out.println(ans.size());
        for (int i = 0; i < ans.size(); i++) {
            System.out.print(ans.get(i));
            if (i != ans.size() - 1) System.out.print(" ");
        }
    }
}