题目连接：

http://www.codeforces.com/contest/632/problem/C

Description

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.

Sample Input

4
abba
abacaba
bcd
er

Sample Output

abacabaabbabcder

Hint

题意

给你n个串，然后你要组合这n个串，使得n个串的字典序最小

题解：

写个CMP就好了~

代码

#include<bits/stdc++.h>
using namespace std;
const int maxn = 5e4+5;
string s[maxn];
bool cmp(string a,string b)
{
    string ab = a+b;
    string ba = b+a;
    return ab<ba;
}
int main()
{
    int n;
    scanf("%d",&n);
    for(int i=0;i<n;i++)
        cin>>s[i];
    sort(s,s+n,cmp);
    for(int i=0;i<n;i++)
        cout<<s[i];
    cout<<endl;
}