#include <iostream>
#include <vector>
#include <string>
#include <cstring>
#include <math.h>
#include <cmath>
#include <limits.h>
#include <map>
#include <unordered_map>
#include <set>
#include <queue>
#include <algorithm>
#include <functional>
#include <stdio.h>
using namespace std;

long long MOD = 1000000007;

int N;

void func( string s ) {

    if ( s.length() == 18 ) { return; }
    if ( N == 0 ) { return; }

    cout << "a" << s << "a" << endl;
    N--;

    for ( char c = 'a'; c <= 'z'; c++ ) {
        func( s+c );
    }
    
}



int main() {    
    cin >> N;

    string s;
    func(s);

    return 0;
}