// No.2707 Bag of Words Encryption
package main

import (
	"fmt"
	"strconv"
	"strings"
)

func main() {
	var n int
	var s string
	fmt.Scan(&n, &s)

	m := map[rune]int{}
	for i := rune('A'); i <= rune('Z'); i++ {
		m[i] = 0
	}
	for j := 0; j < n; j++ {
		r := rune(s[j])
		m[r] += 1
	}
	c := make([]string, len(m))
	for k, v := range m {
		c[k-rune('A')] = strconv.Itoa(v)
	}
	fmt.Println(strings.Join(c, ""))
}