#include<bits/stdc++.h>

 #define pa pair<int,int>

 #define CLR(a,x) memset(a,x,sizeof(a))

 using namespace std;

 typedef long long ll;

 const int maxn=1e5+;

 inline ll rd(){

     ll x=;char c=getchar();int neg=;

     while(c<''||c>''){if(c=='-') neg=-;c=getchar();}

     while(c>=''&&c<='') x=x*+c-'',c=getchar();

     return x*neg;

 }

 int N;

 char c[maxn];

 int main(){

     //freopen(".in","r",stdin);

     int i,j,k;

     N=rd();

     scanf("%s",c+);

     sort(c+,c+N+);

     printf("%s",c+);

     return ;

 }