n=int(input())
str=list(input())
str.sort()
print(''.join(str))148A - Insomnia cure | 1650A - Deletions of Two Adjacent Letters |
1512A - Spy Detected | 282A - Bit++ |
69A - Young Physicist | 1651A - Playoff |
734A - Anton and Danik | 1300B - Assigning to Classes |
1647A - Madoka and Math Dad | 710A - King Moves |
1131A - Sea Battle | 118A - String Task |
236A - Boy or Girl | 271A - Beautiful Year |
520B - Two Buttons | 231A - Team |
479C - Exams | 1030A - In Search of an Easy Problem |
158A - Next Round | 71A - Way Too Long Words |
160A - Twins | 1A - Theatre Square |
1614B - Divan and a New Project | 791A - Bear and Big Brother |
1452A - Robot Program | 344A - Magnets |
96A - Football | 702B - Powers of Two |
1036A - Function Height | 443A - Anton and Letters |