#include <iostream>
using namespace std;

const int kMAX_N = 100;

int N;
int start[kMAX_N];
string S[kMAX_N];

bool IsBetter(int index1, int index2) {
    string str1 = S[index1].substr(start[index1]),
           str2 = S[index2].substr(start[index2]);
    int len1 = str1.size(),
        len2 = str2.size();
    if (str1.substr(0, min(len1, len2)) == str2.substr(0, min(len1, len2))) {
        return len1 >= len2;
    } else {
        return str1 < str2;
    }
}

int main() {
    cin >> N;

    for (int i = 0; i < N; i++) {
        cin >> S[i];
    }

    string ans = "";
    while (true) {
        int index = -1;
        for (int i = 0; i < N; i++) {
            if (start[i] == S[i].size()) continue;
            if (index == -1 || IsBetter(i, index)) {
                index = i;
            }
        }
        if (index < 0) break;
        ans.push_back(S[index][start[index]]);
        start[index]++;
    }
    cout << ans << endl;

    return 0;
}