#include <bits/stdc++.h>

#define nmax 20

#define lmax 30005

#define inf 1<<29

using namespace std;

char s[nmax][lmax],o[lmax];

char af[nmax*lmax];

int n,v[(1<<18)+50][nmax];

short q[(1<<18)+50][nmax];

int cost[nmax][nmax],com[nmax][nmax],t[nmax];

int pi[lmax],a[nmax];

int sol,soli,solj,poz[nmax],cnt[nmax],soll;





int main()

{

    int i,j,l,k,p;

    freopen("adn.in","r",stdin);

    freopen("adn.out","w",stdout);

    scanf("%d",&n);

    for (i=0;i<n;i++) {

        memset(o,0,sizeof(o));

        scanf("%s",&o);

        memcpy(s[i]+1,o,lmax);

        while (s[i][t[i]+1])

            t[i]++;

    }

    for (i=0;i<n;i++) {

        pi[1]=0;

        a[i]=1;

        for (k=2,l=0;s[i][k];k++) {

            while (l&&s[i][k]!=s[i][l+1])

                l=pi[l];

            if (s[i][k]==s[i][l+1])

                l++;

            pi[k]=l;

        }

        for (j=0;j<n&&a[i];j++)

            if (i!=j) {

                for (k=1,l=0;s[j][k]&&a[i];k++) {

                    while (l&&s[j][k]!=s[i][l+1])

                        l=pi[l];

                    if (s[j][k]==s[i][l+1])

                        l++;

                    if (l==t[i]) {

                        if (l==t[j])

                            a[min(i,j)]=0;

                        else

                            a[i]=0;

                    }

                }



                com[j][i]=l;

                cost[j][i]=t[i]-com[j][i];

            }

    }

    for (i=0;i<n;i++)

        if (a[i]) {

            v[1<<i][i]=t[i];

            soli+=1<<i;

        }

    for (i=0;i<(1<<n);i++)

        for (j=0;j<n;j++)

            if (!v[i][j])

                v[i][j]=inf;

    for (i=0;!a[i];i++);

    for (i=1<<i;i<soli;i++)

        for (j=0;j<n;j++)

            if (a[j])

            if ((i&(1<<j))==0) {

                p=i+(1<<j);

                for (k=0;k<n;k++)

                    if (a[k]&&v[i][k]!=inf)

                    if (i&(1<<k))

                        if (v[i][k]+cost[k][j]<v[p][j]) {

                            v[p][j]=v[i][k]+cost[k][j];

                            q[p][j]=k;

                        }

            }

    sol=inf;

    for (i=0;i<n;i++)

        if (v[soli][i]<sol) {

            sol=v[soli][i];

            solj=i;

        }

    int m=0;

    for (i=0;i<n;i++)

        if (a[i])

            m++;

    while (m) {

        if (!cnt[m+1]) {

            poz[m]=solj;

            cnt[m--]=t[solj];

            k=q[soli][solj];

            sol-=t[solj];

            soli-=1<<solj;

            soll=solj;solj=k;

        }

        else {

            poz[m]=solj;

            cnt[m]=t[solj]-com[poz[m]][poz[m+1]];

            m--;

            k=q[soli][solj];

            soli-=1<<solj;

            soll=solj;solj=k;

            sol-=cnt[m+1];

        }

    }

    for (i=1;cnt[i];i++)
        strncpy(af+strlen(af),s[poz[i]]+1,cnt[i]);

    printf("%s",af);

    return 0;

}