UVA 10905 - Children's Game

/***
Md. Nazmul Hasan
Shahjalal University of Science & Technology,Sylhet.
hasan08sust@gmail.com
***/
#include<iostream>
#include<cstdio>
#include<stack>
#include<queue>
#include<map>
#include<vector>
#include<algorithm>
#include<cstring>
#include<sstream>
#include<cmath>
#include <iomanip>
using namespace std ;
typedef long long ll ;
typedef int in ;
typedef unsigned long long ull ;
const double pi = 2*acos(0) ;
#define maxi 40000
#define pf printf
#define sc scanf
#define pb push_back
#define MEM(x,y) (memset((x),(y),sizeof(x)))
#define MIN(x,y) ((x) < (y) ? (x) : (y))
#define MAX(x,y) ((x) > (y) ? (x) : (y))
#define load(array,size)  for(int i=0 ; i<size ; i++) cin>>array[i]  ;
#define new_line  pf("\n")
#define clear_data(array) memset(array,0,sizeof(array))
#define highest_int 2147483647


struct str{
  string str;
};

bool operator < (const str & a, const str & b)
{
    return a.str + b.str > b.str + a.str ;
}

int main()
{
   int n;
   while(sc("%d",&n))
   {
       if(n==0)
        break;
        str num[55];

       for(int i=0 ; i<n; i++)
       {
           cin>>num[i].str ;
       }

       sort(num, num+n);

       for(int i=0 ; i<n ; i++)
        cout<<num[i].str ;

       cout<<endl ;
   }
    return 0;
}