#include <cstring>
#include <iostream>
#include <algorithm>
#include <queue>

using namespace std;

int n;
std::string a[1001];
std::vector<int> e[1001];
int ind[1001];
int rnd[1001];
bool used[1001];

void dfs(int s,string curr, int count) {
	if (count == n) {
		curr[curr.length() - 1] = ' '; // 把最后一个 '.' 去掉。
		std::cout << curr;
		exit(0);
	}
	for (auto i : e[s])
		if (!used[i]) {
			used[i] = true;
			dfs(i, curr + a[i] + '.', count + 1);
			used[i] = false;
		}
}
int main() {
	std::cin >> n;
	for (int i = 1; i <= n; ++i) {
		std::cin >> a[i];
		++ind[a[i][0]];
		++rnd[a[i][a[i].length() - 1]];
	}
	std::sort(a + 1, a + n + 1);
	for (int i = 1; i <= n; ++i)
		for (int j = 1; j <= n; ++j)
			if (i != j && a[i][a[i].length() - 1] == a[j][0])
				e[i].push_back(j);
	for (int i = 1; i <= n; ++i)
		if (ind[a[i][0]] == rnd[a[i][0]] + 1) {
			used[i] = true;
			dfs(i, a[i] + '....