#include<bits/stdc++.h>
using namespace std;
int main(){
    int n;
    cin>>n;
    string s;
    cin>>s;
    string ls;//左边小写字母的串
    string cs;//中间数字的串
    string rs;//右边大写字母的串
    for(int i=0;i<n;i++){
        if(s[i]>='A' && s[i] <='Z'){
            rs+=s[i];
        }else if(s[i]>='a' && s[i]<='z'){
            ls+=s[i];
        }else{
            cs+=s[i];
        }
    }
    cout<<ls<<cs<<rs;//组合输出即可
}