#include <iostream>
#include <bits/stdc++.h>
 
using namespace std;
 
int main()
{
   ios_base::sync_with_stdio(false);
   cin.tie(NULL);
 
   int sizee ;
   cin >> sizee ;
   string s ;
   cin >> s ;
   int count[123]={0} ;
 
   for (int x=0 ; x<sizee ; x++)
   {
       count[s[x]] ++ ;
   }
   int y=97 ;
   int x=sizee ;
   while(x)
   {
       for (int z=0 ; z<count[y] ; z++)
       {
           char c=y ;
           cout << c ;
           x-- ;
       }
       y++ ;
   }
 
 
    return 0;
}

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