#include<bits/stdc++.h>
using namespace std;
int n;
string s[21];
inline int read() {
	int x=0,f=1;
	char ch=getchar();
	while (ch<'0'||ch>'9') {
		if (ch=='-') f=-1;
		ch=getchar();
	}
	while (ch>='0'&&ch<='9') {
		x=x*10+ch-48;
		ch=getchar();
	}
	return x*f;
}
bool cmp(string x,string y){
	return x+y>y+x;
}
signed main(){
	ios::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
	n=read();
	for(int i=1;i<=n;i++)cin>>s[i];
	sort(s+1,s+n+1,cmp);
	for(int i=1;i<=n;i++)cout<<s[i];
	cout<<endl;
	return 0;
}