#Uses python3

import sys

def compareLeadingDigits(num1, num2):
    return (int) (num1 + num2) > (int) (num2+num1)


def getLargestNumber(nums):
    result = ""
    maxDigit = "0"
    indexHolder = 0
    while len(nums) > 0:
        for i in range(0, len(nums)):
            if compareLeadingDigits(str(nums[i]), maxDigit):
                maxDigit= str(nums[i])
                indexHolder = i;
        result = result + maxDigit
        maxDigit = "0"
        del nums[indexHolder]
    return result

if __name__ == '__main__':
    input = sys.stdin.read()
    data = input.split()
    a = data[1:]
    print(getLargestNumber(a))