include<bits/stdc++.h>

using namespace std; bool cmp(int &b,int &c){

return b>c;

} int main(){

freopen("chart.in","r",stdin);
freopen("chart.out","w",stdout);
int n;
char c[101];
cin>>n;
for(int i=0;i<n;i++)cin>>c[i];
sort(c,c+n,cmp);
for(int i=0;i<n;i++)cout<<c[i];
return 0;

}