#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>

#define MAX_LENGTH 1000

int cmp(const void* a, const void* b) {
    char* f = (char*)a;
    char* s = (char*)b;
    if (strlen(f) == strlen(s)) {
        while (*f == *s) {
            f++;
            s++;
        }
        return *f - *s;
    }
    return strlen(f) - strlen(s);
}

char* make_palindrome(char* word, int k, char add) {
    char* c = malloc(sizeof(char) * 1000 + 2 * k);
    for (int j = 0; j < k; j++) {
        c[j] = add;
    }
    strcpy(c + k, word);
    char* p = malloc(k * sizeof(char) + 1);
    for (int i = 0; i < k; i++) {
        p[i] = add;
    }
    p[k] = '\0';
    strcat(c + k + strlen(word), p);
    return c;
}

int main() {
    int n;
    scanf("%d", &n);

    char palindromes[MAX_LENGTH][1000];

    int m = 0;



    char even[500][32] = {{"aa"}, {"bb"}};
    char odd[500][32] = {{"a"}, {"b"}};

    int q = 1;
        char temp[500][32];
        char temp2[500][32];
    for (int j = 0; j < 6; j++) {
        int l = 0;
        for (int i = 0; i < pow(2, q); i++) {
            strcpy(temp[l], make_palindrome(even[i], 1, 'a'));
            strcpy(temp[l + 1], make_palindrome(even[i], 1, 'b'));
            strcpy(temp2[l], make_palindrome(odd[i], 1, 'a'));
            strcpy(temp2[l + 1], make_palindrome(odd[i], 1, 'b'));
            l += 2;
        }
        for (int i = 0; i < pow(2, q + 1); i++) {
            strcpy(even[i], temp[i]);
            strcpy(odd[i], temp2[i]);
            strcpy(palindromes[m++], temp[i]);
            strcpy(palindromes[m++], temp2[i]);
        }
        q++;
        memset(temp, 0, sizeof(temp));
        memset(temp2, 0, sizeof(temp2));
    }


    strcpy(palindromes[m++], "");
    strcpy(palindromes[m++], "a");
    strcpy(palindromes[m++], "b");
    strcpy(palindromes[m++], "bb");
    strcpy(palindromes[m++], "aa");

    qsort(palindromes, m, 1000, cmp);

     for (int i = 0; i < n; i++) {
            printf("%4d. %s\n", i + 1, palindromes[i]);
        }


}