/*
A string S is given consisting of lowercase alphabetical characters only. You need to return a sorted string using Count Sort.

Input format
First line will contain a single integer n representing size of the given string.

Second line will contain a single string S of size n.

Output format
Output the string in a single line.

Sample Input 1
10

abcdeedcba

Sample Output 1
aabbccddee

Constraints
1<=n<=10^6

String S will contain lowercase alphabetical characters only
*/

/**
 * @param {number} n
 * @param {string} s
 * @return {string}
 */
function countSort(n, str) {
  let frequencyCount = new Array(26).fill(0);
  for (let i = 0; i < n; i++) {
    const charCode = str.charCodeAt(i) - "a".charCodeAt(0);
    frequencyCount[charCode]++;
  }
  let sortedString = "";
  for (let i = 0; i < 26; i++) {
    for (let j = 0; j < frequencyCount[i]; j++) {
      sortedString = sortedString + String.fromCharCode("a".charCodeAt(0) + i);
    }
  }
  return sortedString;
}

function main() {
    let n = parseInt(readLine());
    let str = readLine();

    let storedString = countSort(n, str);
    print(storedString)
}