import java.util.*;

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

        if (s.charAt(n - 1) == '0') {
            System.out.print(-1);
            return;
        }

        List<Integer> result = new ArrayList<>();
        int p1 = 0;
        int p2 = 0;

        for (int i = 0; i < n; i++) {
            if (s.charAt(i) == '1') {
                if (p1 == p2) {
                    p1 = p2 = i + 1;
                    result.add(i + 1);
                } else {
                    result.add(i + 1);
                    p2 = i + 1;
                    for(int j = p1+1;j<p2;j++){
                        result.add(j);
                    }
                    p1 = i+1;
                }
            } else {
                p2++;
            }

        }

        for (int tmp : result) {
            System.out.print(tmp + " ");
        }
    }
}