Problem: You're given a list of n strings a1, a2, ..., an. You'd like to concatenate them together in some order such that the resulting string would be lexicographically smallest.

Given the list of strings, output the lexicographically smallest concatenation.

Input

The first line contains integer n — the number of strings (1 ≤ n ≤ 5·104).

Each of the next n lines contains one string ai (1 ≤ |ai| ≤ 50) consisting of only lowercase English letters. The sum of string lengths will not exceed 5·104.

Output

Print the only string a — the lexicographically smallest string concatenation.

Examples

Input

4
abba
abacaba
bcd
er


Output

abacabaabbabcder


Input

5
x
xx
xxa
xxaa
xxaaa


Output

xxaaaxxaaxxaxxx


Input

3
c
cb
cba


Output

cbacbc

Solution (in PYTHON3):

Solution:
from sys import stdout, stdin, setrecursionlimit
from bisect import insort,bisect_right,bisect_left
from io import BytesIO, IOBase
from collections import *
from itertools import *
from random import * 
from string import *
from queue import *
from heapq import *
from math import *
from re import *
from os import *

####################################---fast-input-output----#########################################


class FastIO(IOBase):
    newlines = 0

    def __init__(self, file):
        self._fd = file.fileno()
        self.buffer = BytesIO()
        self.writable = "x" in file.mode or "r" not in file.mode
        self.write = self.buffer.write if self.writable else None

    def read(self):
        while True:
            b = read(self._fd, max(fstat(self._fd).st_size, 8192))
            if not b:
                break
            ptr = self.buffer.tell()
            self.buffer.seek(0, 2), self.buffer.write(b), self.buffer.seek(ptr)
        self.newlines = 0
        return self.buffer.read()

    def readline(self):
        while self.newlines == 0:
            b = read(self._fd, max(fstat(self._fd).st_size, 8192))
            self.newlines = b.count(b"\n") + (not b)
            ptr = self.buffer.tell()
            self.buffer.seek(0, 2), self.buffer.write(b), self.buffer.seek(ptr)
        self.newlines -= 1
        return self.buffer.readline()

    def flush(self):
        if self.writable:
            write(self._fd, self.buffer.getvalue())
            self.buffer.truncate(0), self.buffer.seek(0)


class IOWrapper(IOBase):
    def __init__(self, file):
        self.buffer = FastIO(file)
        self.flush = self.buffer.flush
        self.writable = self.buffer.writable
        self.write = lambda s: self.buffer.write(s.encode("ascii"))
        self.read = lambda: self.buffer.read().decode("ascii")
        self.readline = lambda: self.buffer.readline().decode("ascii")


stdin, stdout = IOWrapper(stdin), IOWrapper(stdout)
graph, mod, szzz =  {}, 10**9 + 7, lambda: sorted(zzz())
def getStr(): return input()
def getInt(): return int(input())
def listStr(): return list(input())
def getStrs(): return input().split()
def isInt(s): return '0' <= s[0] <= '9'
def input(): return stdin.readline().strip()
def zzz(): return [int(i) for i in input().split()]
def output(answer, end='\n'): stdout.write(str(answer) + end)
def lcd(xnum1, xnum2): return (xnum1 * xnum2 // gcd(xnum1, xnum2))

def primeNums():
    N = 10**5
    SN = int(sqrt(N))
    sieve = [i for i in range(N+1)]
    sieve[1] = 0
    for i in sieve:
        if i > SN:
            break
        if i == 0:
            continue
        for j in range(2*i, N+1, i):
            sieve[j] = 0
    prime = [i for i in range(N+1) if sieve[i] != 0] 
    return prime
def primeFactor(n):
    lst = []
    mx=int(sqrt(n))+1
    for i in prime:
        if i>mx:break
        while n%i==0:
            lst.append(i)
            n//=i
    if n>1:
        lst.append(n)
    return lst    

dx = [-1, 1, 0, 0, 1, -1, 1, -1]
dy = [0, 0, 1, -1, 1, -1, -1, 1]
daysInMounth = [31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31]


#################################################---Some Rule For Me To Follow---#################################
"""
    --instants of Reading problem continuously try to understand them.

    --If you Know some-one , Then you probably don't know him !

    --Try & again try, maybe you're just one statement away!


"""
##################################################---START-CODING---###############################################

def mergeSort(s):
    if len(s) == 1:
        return s
    s1= mergeSort(s[:len(s)//2])
    s2= mergeSort(s[len(s)//2:])
    return merge(s1,s2)
def merge(s1,s2):
    lst=[]
    ind1=0
    ind2=0
    while ind1!=len(s1) and ind2 != len(s2):
        if str(s1[ind1])+str(s2[ind2])>str(s2[ind2])+str(s1[ind1]):
            lst.append(s2[ind2])
            ind2+=1
        else:
            lst.append(s1[ind1])
            ind1+=1
    if ind1!=len(s1):
        lst.extend(s1[ind1:])
    else:
        lst.extend(s2[ind2:])
    return lst

n = getInt()

lst=[]
for i in range(n):
    lst.append(getStr())
print(''.join(mergeSort(lst)))