#include <fstream>
#include <iostream>
#include <string>
#include <algorithm>
#define INF 0x3f3f3f3f
using namespace std;
int pi[30005], graph[18][18], st, C[18][(1 << 18)], before[18][(1 << 18)], map[18];
bool not_show[18];
string adn[18];
int main()
{
int n;
ifstream in("adn.in");
in >> n;
for(int i = 0; i < n; ++i)
{
in >> adn[i];
}
in.close();
for(int i = 0; i < n; ++i) 
{
int w_size = adn[i].size();
int back = 0, pos = w_size-3;
pi[w_size-1] = -1;
pi[w_size-2] = 0;
while (pos >= 0)
{
if(adn[i][pos+1] == adn[i][w_size-back-1])
{
++back;
pi[pos] = back;
--pos;
}
else
if(back > 0)
back = pi[w_size-back-1];
else
{
pi[pos] = 0;
--pos;
}
}
for(int j = 0; j < n; ++j)
{
if(i!=j&&(!not_show[i]))
{
int now = 0, pos = 0, w_size = adn[i].size(), s_size = adn[j].size();
while (now < s_size)
{
if((now+pos < s_size)&&(adn[i][w_size-1-pos] == adn[j][s_size-1-(now+pos)])||(now+pos >= s_size))
{
if(pos == w_size-1)
{
if(now+pos < s_size)
{
not_show[i] = true;
break;
}
graph[i][j] = s_size - now;
break;
}
else
++pos;
}
else
{
now = now + pos - pi[w_size-1-pos];
if(pi[w_size-1-pos] > -1)
pos = pi[w_size-1-pos];
else
pos = 0;
}
}
}
}
}
int Not = 0;
for(int i = 0; i < n; ++i)
if(!not_show[i])
map[Not++] = i;
for(int i = 1; i < (1<<Not); ++i)
{
for(int j = 0; j < Not; ++j)
{
if(!(i&(1<<j)))
{
C[j][i] = -1;
for(int k = 0; k < Not; ++k)
{
if(j!=k && ((1<<k)&i))
{
if(C[k][i-(1<<k)] + graph[map[j]][map[k]] > C[j][i])
{
C[j][i] = C[k][i-(1<<k)] + graph[map[j]][map[k]];
before[j][i] = k;
}
}
}
}
}
}
int max = -1, f, i, k;
for(int i = 0; i < Not; ++i)
if(C[i][(1<<Not)-1-(1<<i)] > max)
{
max = C[i][(1<<Not)-1-(1<<i)];
f = i;
}
ofstream out("adn.out");
out << adn[map[f]];
max = (1<<Not)-1-(1<<f);
while(max > 0)
{
i = before[f][max];
for(int j = graph[map[f]][map[i]]; j < adn[map[i]].size(); ++j)
out << adn[map[i]][j];
max -= (1<<i);
f = i;
}
out.close();
return 0;
}