a = int(input())
b = input()
b = b.split(' ')
for i in range(a):
    for j in range(i + 1, a):
        if b[j] + b[i] > b[i] + b[j]:
            b[j], b[i] = b[i], b[j]
stranswer=''
for k in b:
    stranswer+=k
print(int(stranswer))