#include <bits/stdc++.h>
using namespace std;
 
vector<string> v;
 
bool cmp(string a,string b){
	int La=a.length(); int Lb=b.length();
	if( La==Lb ) return a>b;
 
	int pa=0; int pb=0;;
	for(int i=0;i<La*Lb;i++){
		if( a[pa]!=b[pb] )
			return a[pa]>b[pb];
		pa++; pb++;	
		if( pa==La ) pa=0;
		if( pb==Lb ) pb=0;
	}
	return a>b;
}
 
int main() {
	int N;
	while( cin>>N and N>0 ){
		v.clear();
		for(int i=0;i<N;i++){
			string a;
			cin>>a;
			v.push_back(a);
		}
		sort( v.begin(),v.end(),cmp );
		for(int i=0;i<N;i++)
			cout<<v[i];
		cout<<'\n';	
	}
}

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NAoxMjMgMTI0IDU2IDkwCjUKMTIzIDEyNCA1NiA5MCA5CjUKOSA5IDkgOSA5CjMKMTIgMTIzIDEyMzEKMAo=

4
123 124 56 90
5
123 124 56 90 9
5
9 9 9 9 9
3
12 123 1231
0