import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Scanner;

public class LargestNumber {

	public static void main(String[] args) {
		Scanner scanner = new Scanner(System.in);
		int n = scanner.nextInt();
		String[] a = new String[n];
		for (int i = 0; i < n; i++) {
			a[i] = scanner.next();
		}
		System.out.println(getLargestNumber(a));
	}

	public static String getLargestNumber(String[] numbers) {
		List<String> numList = new ArrayList<String>(Arrays.asList(numbers));
		String result = "";
		String maxDigit = "0";
		int indexHolder = 0;
		while (numList.size() > 0) {
			for (int i = 0; i < numList.size(); i++) {
				if (compareLeadingDigit(numList.get(i), maxDigit)) {
					maxDigit = numList.get(i);
					indexHolder = i;
				}
			}
			result = result + maxDigit;
			maxDigit = "0";
			numList.remove(indexHolder);
		}
		return result;
	}

	public static boolean compareLeadingDigit(String s, String maxDigit) {
//Oh my god, the algorithm for this comparison was so clever mentioned 
//by bytwigorlimerick in this page:
//https://courses.edx.org/courses/course-v1:UCSanDiegoX+ALGS200x+2T2017/discussion/forum/course/threads/5a427dbf44a15008cd000701
//This solved the problem nicely and easily, so elegant!
		return Integer.parseInt(s + maxDigit) > Integer.parseInt(maxDigit + s);
//		if (s.length() == maxDigit.length())
//			return Integer.parseInt(s) > Integer.parseInt(maxDigit);
//		if (s.length() < maxDigit.length()) {
//			if (s.charAt(0) > maxDigit.charAt(0)) {
//				return true;
//			} else if (s.charAt(0) < maxDigit.charAt(0)) {
//				return false;
//			} else if (s.charAt(0) > maxDigit.charAt(1)) {
//				return true;
//			} else if (s.length() == 1) {
//				if (s.charAt(0) > maxDigit.charAt(1))
//					return true;
//				else
//					return false;
//			} else
//				return compareLeadingDigit(s.substring(1), maxDigit.substring(1));
//		} else {
//			return !compareLeadingDigit(maxDigit, s);
//		}
	}

}