#include<bits/stdc++.h>
using namespace std;
struct node
{
    char s[210];
}a[1010];
bool cmp(node aa,node bb)
{
    char a1[210],b1[210];
    strcpy(a1,aa.s);strcpy(b1,bb.s);
    strcat(a1,bb.s);strcat(b1,aa.s);
    return strcmp(a1,b1)>0;
}
int main()
{
    freopen("brick.in","r",stdin);
    freopen("brick.out","w",stdout);
    int n,i;
    scanf("%d",&n);
    for(i=1;i<=n;i++)scanf("\n%s",a[i].s);
    sort(a+1,a+n+1,cmp);
    for(i=1;i<=n;i++)printf("%s",a[i].s);
    fclose(stdin);
    fclose(stdout);
    return 0;
}