#include <iostream>
#include <algorithm>
#include <string>
using namespace std;
 
int main() {
    ios::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);
    int n;
    string s;
    cin >> n;
    cin >> s;
    sort(s.begin(), s.end());
    cout <<s<< endl;
 
 
    return 0;
}