/* Topcoder SRM 708, D2 500-pointer
 * BuildingStrings
 * James S. Plank
 * Mon Feb 20 15:59:09 EST 2017
 */

#include <string>
#include <vector>
#include <iostream>
#include <cstdio>
#include <cstdlib>
using namespace std;

typedef vector <string> SVec;

class BuildingStrings
{
    public:
        vector <string> findAny(int K);
};

vector <string> BuildingStrings::findAny(int K)
{
    int i, score;
    vector <string> rv;
    string s;

    /* Create the string s */

    for (i = 0; i < 50; i++) s.push_back('a' + i%26);

    /* Do steps 2 and 3 from the writeup -- while s's score is less than
       or equal to K, add it to the return vector and decrement the score 
       from K.  While s's score is greater than K, remove the last letter
       from s.  Do this until K <= 50. */

    while (K > 50) {
      score = (s.size() > 26) ? (26 * s.size()) : (s.size() * s.size());
      while (score <= K) {
        rv.push_back(s);
        K -= score;
      }
      s.pop_back();
    }

    /* Step 4: K is <= 50, so you can create a string of length K with
       a single character.  Its score will be K. */

    if (K > 0) {
        s.clear();
        s.resize(K, 'a');
        rv.push_back(s);
    }

    return rv;
}