import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);sc.nextInt();
        int[] cnt = new int[26];
        for(char c: sc.next().toCharArray()) {
            cnt[(c - 'A')]++;
        }
        StringBuilder s = new StringBuilder();
        for(int i:cnt) {
            s.append(i);
        }
        System.out.println(s);
    }
}