from typing import List

def compare(a: str, b: str) -> bool:
    return a + b > b + a

def main():
    N = int(input())
    numbers: List[str] = [input() for _ in range(N)]
    numbers.sort(key=lambda x: (x * 2), reverse=True)
    result = ''.join(numbers)
    if result[0] == '0':
        result = "0"
    print(result)

if __name__ == "__main__":
    main()