import java.util.Scanner;

public class Main {
    public static void main(String []args){
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        sc.nextLine();
        String []strArray = sc.nextLine().split(" ");

        for(int k = 0;k<n;k++){
            for(int m = 0;m<n-1-k;m++){
                if(!sort1(strArray[m], strArray[m+1])){
                    String temp = strArray[m];
                    strArray[m] = strArray[m+1];
                    strArray[m+1] = temp;
                }
            }
        }
    for(int i = 0;i<n;i++)    System.out.print(strArray[i]);
    }

   
    public static boolean sort1(String str1,String str2){
        char []char1 = (str1+str2).toCharArray();
        char []char2 = (str2+str1).toCharArray();
        for(int i = 0;i<char1.length;i++){
            if(char1[i]>char2[i]) return true;
            else if(char1[i]<char2[i]) return false;
        }
        return false;
    }
    
}

注意得用String类型,用int会超。