day2

include

using namespace std;

include<string.h>

include<stdio.h>

int main() {
int n;
cin >> n;
string* p = new string[n];
for (int i = 0; i < n; i++) {
cin >> p[i];
}
string m;
for (int i = 0; i < n; i++) {
for (int j = i + 1; j < n; j++) {
if (p[i] < p[j]) {
m = p[j];
p[j] = p[i];
p[i] = m;

		}
	}
	
}
string d;
for (int i = 0; i < n; i++) {
	d = d+p[i];
}
cout << d << endl;
delete[]p;
return 0;

}