n=eval(input())
str_code=input().split(' ')
def code(x,y):
    return x+y<y+x
for i in range(len(str_code)-1):
    for j in range(i,len(str_code)):
        if code(str_code[i],str_code[j]):
            str_temp=str_code[i]
            str_code[i]=str_code[j]
            str_code[j]=str_temp
for i in range(len(str_code)):
    print(eval(str_code[i]),end='')