import java.util.Arrays;
import java.util.Comparator;
import java.util.Stack;

public class MaxMergedNumberForIntArray {

   private static Comparator<Integer> MAX_MERGED_COMPARATOR = (x, y) -> {

      final Stack<Integer> xDigits = getStuckWithDigits(x);
      final Stack<Integer> yDigits = getStuckWithDigits(y);

      while (!xDigits.empty() && !yDigits.empty()) {
         final Integer xValue = xDigits.pop();
         final Integer yValue = yDigits.pop();

         if (xValue > yValue) {
            return 1;
         } else if (xValue < yValue) {
            return -1;
         }
      }
      if (xDigits.empty() && yDigits.empty()) {
         return 0;
      } else if (xDigits.empty() && !yDigits.empty()) {
         return 1;
      } else {
         return -1;
      }
   };

   private static Stack<Integer> getStuckWithDigits(Integer o1) {
      final Stack<Integer> o1Integers = new Stack<>();
      while (o1 > 0) {
         o1Integers.push(o1 % 10);
         o1 /= 10;
      }
      return o1Integers;
   }


   public static String maxMergedNumber(Integer... numbers) {
      Arrays.sort(numbers, MAX_MERGED_COMPARATOR.reversed());

      StringBuilder sb = new StringBuilder();
      for (Integer number : numbers) {
         sb.append(number);
      }
      return sb.toString();
   }
}