#include <stdio.h>
#include <string.h>
#include <limits.h>
#include <stdlib.h>

void main(){
    FILE * fi = fopen("adn.in","rt");
    unsigned char n, i, j;
    fscanf( fi, "%hhd\n" , &n);
    char secv[n][30000];
    n--;
    for( i  = 0 ; i < n ; i++ )
        fscanf(fi,"%s\n",secv[i]);
    fscanf(fi,"%s",secv[n]);
    fclose(fi);
    n++;
    unsigned short metaData[n][30000], ti, len,
        wi;
    for( i = 0 ; i < n ; i++ ){
        len = strlen(secv[i]);
        metaData[i][0] = 0;
        wi=0;
        ti = 1;
        while( ti < len ){
            if( secv[i][ti] == secv[i][wi] ){
                wi++;
                metaData[i][ti] = wi;
                ti++;
            } else if( wi > 0 )
                wi = metaData[i][wi-1];
            else {
                metaData[i][ti] = 0;
                ti++;
            }
        }
    }
    unsigned short costs[n][n], lenMax,
        lenMin;
    unsigned char deElim[n], max, min, k = 0;
    for( i = 0 ; i < n ; i++ )
        deElim[i] = 0;
    n--;
    for( i = 0 ; i < n ; i++ )
        for( j = i + 1 ; j <= n && !deElim[i] ; j++ )
            if( !deElim[j] ){
                if( strlen(secv[i]) > strlen(secv[j]) ){
                    max = i;
                    min = j;
                } else {
                    max = j;
                    min = i;
                }
                wi = ti = len = 0;
                lenMax = strlen(secv[max]);
                lenMin = strlen(secv[min]);

                while( ti < lenMax && wi < lenMin )
                    if( secv[min][wi] == secv[max][ti] ){
                        wi++;
                        ti++;
                    } else if( wi != 0){
                        wi = metaData[min][wi-1];
                        len = ti;
                    } else {
                        ti++;
                        len = ti;
                    }
                if( wi == lenMin){
                    deElim[min] = 1;
                    k++;
                }
                else{
                    costs[max][min] = lenMax - len;
                    wi = len = 1;
                    ti = 0;
                    while( wi < lenMin ){
                        if( secv[min][wi] == secv[max][ti] ){
                            wi++;
                            ti++;
                        } else if( ti != 0 ) {
                            ti = metaData[max][ti-1];
                            len = wi;
                        } else {
                            wi++;
                            len = wi;
                        }
                    }
                    costs[min][max] = lenMin - len;
                }
            }
    n++;

    unsigned char indexes[n-k];
    i = j = 0;
    while( i < n ){
        if(!deElim[i]){
            indexes[j] = i;
            j++;
        }
        i++;
    }
    n = j;

    unsigned int mask, maxLen = 1<<n;
    int variante[n][maxLen];
    unsigned char after[n][maxLen];
    for( i = 0 ; i < n ; i++ )
        for( mask = 0 ; mask < maxLen ; mask++ )
            variante[i][mask] = INT_MIN;


    for( i = 0 ; i < n ; i++ ){
        for( j = 0 ; j < i ; j++ ){
            variante[i][(1<<i)+(1<<j)] = costs[indexes[i]][indexes[j]];
            after[i][(1<<i)+(1<<j)] = j;
        }
        for( j = i+1 ; j < n ; j++ ){
            variante[i][(1<<i)+(1<<j)] = costs[indexes[i]][indexes[j]];
            after[i][(1<<i)+(1<<j)] = j;
        }
    }


    for( mask = 3 ; mask < maxLen ; mask ++ )
        for( i = 0 ; i < n ; i++ )
            if( mask & ( 1 << i ) ){
                for( j = 0 ; j < i ; j++ ){
                    /*printf("i=%d j=%d mask=%d indexes[i]=%d indexes[j]=%d (%d < %d + %d)\n",
                        i , j , mask ,indexes[i], indexes[j] ,
                        variante[i][mask],
                        costs[indexes[i]][indexes[j]],
                        variante[j][mask ^ ( 1 << i )]);*/
                    if( ( mask & ( 1 << j ) )  &&
                            variante[i][mask] < costs[indexes[i]][indexes[j]] +
                            variante[j][mask ^ ( 1 << i )] ){
                        variante[i][mask] = costs[indexes[i]][indexes[j]] +
                            variante[j][mask ^ ( 1 << i )];
                        after[i][mask] = j;
                    }
                }
                for( j = i + 1 ; j < n ; j++ ){
                    if( ( mask & ( 1 << j ) ) &&
                            variante[i][mask] < costs[indexes[i]][indexes[j]] +
                            variante[j][mask ^ ( 1 << i )] ){
                        variante[i][mask] = costs[indexes[i]][indexes[j]] +
                            variante[j][mask ^ ( 1 << i )];
                        after[i][mask] = j;
                    }
                }
            }
    maxLen--;
    mask = variante[0][maxLen];
    j = 0;
    for( i = 1 ; i < n ; i++ )
        if( variante[i][maxLen] > mask ){
            mask = variante[i][maxLen];
            j = i;
        }


    mask = maxLen;
    ti = 0;
    fi = fopen("adn.out","wt");
    while(1){
        fprintf(fi,"%s", secv[indexes[j]] + ti );
        n--;
        if( n == 0 )
            break;
        deElim[0] = j;
        j = after[j][mask];
        ti = costs[indexes[deElim[0]]][indexes[j]];
        mask -= (1 << deElim[0]);
    }
    fclose(fi);
}