/*
 *	KMP + Dynamic Programming
 */

//#define DEBUG

#include <cstdio>
#include <cstring>
#ifdef DEBUG
#include <iostream>
using namespace std;
#endif

#define NMAX 20
#define LMAX 30002
#define CFGMAX 262130
#define INF 1000000000
const int mask[]={1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048, 4096, 8192, 16384, 32768, 65536, 131072};

int N;
int length[NMAX],P[NMAX][LMAX];
char seq[NMAX][LMAX];
int com[NMAX][NMAX];
bool mark[NMAX];
int C[CFGMAX][NMAX],last[CFGMAX][NMAX];

void read_data()
{
	char aux[5];
	fgets(aux,5,stdin);
	sscanf(aux,"%d",&N);
#ifdef DEBUG
	cerr<<N<<endl;
#endif
	for(int i=0; i<N; i++)
	{
		fgets(seq[i]+1,LMAX,stdin);
		length[i]=strlen(seq[i]+1)-1;
#ifdef DEBUG
		cerr<<length[i]<<" "<<seq[i]+1;
#endif
	}
}

void prefix(char *sir, int lung, int *P)
{
	int k=0;
	P[1]=0;
#ifdef DEBUG
	cerr<<P[1]<<" ";
#endif
	for(int q=2; q<=lung; ++q)
	{
		while(k>0 && sir[q]!=sir[k+1])
			k=P[k];
		if(sir[q]==sir[k+1])
			k++;
		P[q]=k;
#ifdef DEBUG
		cerr<<P[q]<<" ";
#endif
	}
#ifdef DEBUG
	cerr<<endl;
#endif
}

int KMP(char *sir, int lsir, char *subsir, int lsubsir, int *P)
{
	int k=0;
	for(int q=1; q<=lsir; ++q)
	{
		while(k>0 && sir[q]!=subsir[k+1])
			k=P[k];
		if(sir[q]==subsir[k+1])
			k++;
		if(k==lsubsir)
			return -1; // "subsir" e total continut in "sir"
	}
	return k;
}

void DP()
{
	int cfg=1<<N;
	for(int i=0; i<cfg; ++i)
		for(int j=0; j<N; ++j)
			if(!(i&mask[j]))
				C[i][j]=INF;
			else
				if(i==mask[j])
					C[i][j]=length[j];
				else
				{
					C[i][j]=INF;
					for(int k=0; k<N; ++k)
						if(C[i^mask[j]][k]!=INF && C[i][j]>C[i^mask[j]][k]+length[j]-com[k][j])
						{
							C[i][j]=C[i^mask[j]][k]+length[j]-com[k][j];
							last[i][j]=k;
						}
				}
}

void write_string(char *s, int begin, int end)
{
	for(int i=begin; i<=end; ++i)
		fputc(s[i],stdout);
}

void write(int i, int j)
{
	if(i==mask[j])
		write_string(seq[j],1,length[j]);
	else
	{
		write(i^mask[j],last[i][j]);
		write_string(seq[j],com[last[i][j]][j]+1,length[j]);
	}
}

void write_solution()
{
	int cfg=0, min=INF, p=-1;
	for(int i=0; i<N; i++)
		if(mark[i]==false)
			cfg|=mask[i];
	for(int i=0; i<N; i++)
		if(mark[i]==false && min>C[cfg][i])
		{
			min=C[cfg][i];
			p=i;
		}
	write(cfg,p);
}


int main()
{
	freopen("adn.in","r",stdin);
	freopen("adn.out","w",stdout);
	read_data();
#ifdef DEBUG
	cerr<<"Prefixuri:"<<endl;
#endif
	for(int i=0; i<N; i++)
	{
#ifdef DEBUG
		cerr<<i+1<<": ";
#endif
		prefix(seq[i],length[i],P[i]);
	}
#ifdef DEBUG
	cerr<<"Lungimi maxime comune:"<<endl;
#endif
	for(int i=0; i<N; i++)
	{
		for(int j=0; j<N; j++)
		{
			if(i==j)
				com[i][j]=0;
			else
			{
				com[i][j]=KMP(seq[i],length[i],seq[j],length[j],P[j]);
				if(com[i][j]==-1)
					mark[j]=true;
			}
#ifdef DEBUG
			cerr<<com[i][j]<<" ";
#endif
		}
#ifdef DEBUG
		cerr<<endl;
#endif
	}
	DP();
	write_solution();
	return 0;
}