#include <iostream>
using namespace std;

int main() {
    int n;
    string a ,b ,c1 ,d;
    cin >> n;
    cin >> a;
    for(char c:a){
        if(c >= 'a' && c <= 'z') b += c;
        if(c >= '0' && c <= '9') c1 += c;
        if(c >= 'A' && c <= 'Z') d += c;
    }
    cout << b +c1 +d;
}
// 64 位输出请用 printf("%lld")