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

char *high(char *a, char *b) {
    if (strlen(a) != strlen(b)) {
        int i = 0;
        for (i = 0; i < (strlen(a) > strlen(b) ? strlen(b) : strlen(a)); i++) {
            if (a[i] > b[i]) {
                return a;
            } else if (a[i] < b[i]) {
                return b;
            }
        }
        char *temp1 = strlen(a) > strlen(b) ? a : b;
        char *temp2 = strlen(a) > strlen(b) ? b : a;
        return temp1[i+1] > a[0] ? temp1 : temp2;
    } else {
        char *temp = a;
        for (int i = 0; i < (strlen(a) > strlen(b) ? strlen(b) : strlen(a)); i++) {
            if (a[i] > b[i]) {
                temp = a;
                break;
            } else if (a[i] < b[i]) {
                temp = b;
                break;
            }
        }
        return temp;
    }
}

int judge(char *a, char *b) {
    int flag = 1;
    if ((int)high(a, b) == (int)a) {
        flag = 0;
    }
    return flag;
}

int main() {
    int n = 0;
    scanf("%d", &n);
    if (n != 0) {
        char a[20][10] = {0};
        for (int i = 0; i < n; i++) {
            scanf("%s", a[i]);
        }
        char result[200] = {0};
        for (int i = 0; i < n; i++) {
            for (int j = 0; j < n - 1 - i; j++) {
                if (judge(a[j], a[j+1])) {
                    char temp[10] = {0};
                    strcpy(temp, a[j]);
                    strcpy(a[j], a[j+1]);
                    strcpy(a[j+1], temp);
                }
            }
        }
        for (int i = 0; i < n; i++) {
            strcat(result, a[i]);
        }
        printf("%s\n", result);
    } else {
        printf("%d", 0);
    }
    return 0;
}