Codeforce 632C The Smallest String Concatenation

C. The Smallest String Concatenation

time limit per test

3 seconds

memory limit per test

256 megabytes

input

standard input

output

standard output

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

想到了就能很简单的写出来，想不到，不仅写的复杂，并且还不对。

#include
#include
#include
using namespace std;
struct node
{
	char s[220];//刚开始开小了，一直RE 
}t[510000];
bool cmp(node a,node b)
{
	return strcmp(strcat(a.s,b.s),strcat(b.s,a.s))<0;
}
int main()
{
	int n,i;
	while(scanf("%d",&n)!=EOF)
	{
		for(i=0;i