package com.kloboshki;

import java.util.Arrays;
import java.util.Scanner;

public class Main {
    static void printAllKLength(char[] set, int k) {
        int n = 2;
        printAllKLengthRec(set, "", n, k);
    }

    static void printAllKLengthRec(char[] set,
                                   String prefix,
                                   int n, int k) {
        if (k == 0) {
            System.out.println(prefix);
            return;
        }

        for (int i = 0; i < n; ++i) {
            String newPrefix = prefix + set[i];
            printAllKLengthRec(set, newPrefix,
                    n, k - 1);
        }
    }

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int z = scanner.nextInt();
        String x = scanner.next();
        String y = scanner.next();
        char[] set1 = {x.charAt(0), y.charAt(0)};
        Arrays.sort(set1);
        printAllKLength(set1, z);
    }
}