#include <iostream>
#include <bits/stdc++.h>
using namespace std;

vector<string> commonChars(vector<string>& words) {
    int arr[26] = {0};

    for (int i = 0; i < words[0].size(); i++) {
        arr[words[0][i] - 'a']++;
    }

    vector<string> ans;

    for (int i = 1; i < words.size(); i++) {
        int arr2[26] = {0};

        for (int j = 0; j < words[i].size(); j++) {
            arr2[words[i][j] - 'a']++;
        }

        for (int k = 0; k < 26; k++) {
            arr[k] = min(arr[k], arr2[k]);
        }
    }

    for (int i = 0; i < 26; i++) {
        for (int j = 0; j < arr[i]; j++) {
            ans.push_back(string(1, char('a' + i)));
        }
    }

    return ans;
}

int main() {
    int n;
    cin >> n;

    vector<string> words(n);

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

    vector<string> ans = commonChars(words);

    for (int i = 0; i < ans.size(); i++) {
        cout << ans[i] << " ";
    }

    return 0;
}