#include <iostream>
#include <cstdio>
#include <vector>
#include <algorithm>
#include <utility>
#include <string>
#include <iterator>

using namespace std;

const int LIMIT = 7e4;

int main() {
	int n;

	cin >> n;
	vector<long long> counts(LIMIT, 0);

	long long half;
	for (long long i = 0; i < counts.size(); i += 2) {
		half = i / 2;
		counts[i] = half * (half + 1);
		counts[i + 1] = (half + 1) * (half + 1);
	}

	string ans;
	int c_idx = 0;

	while (n > 0) {
		auto it = upper_bound(counts.begin(), counts.end(), n);
		it--;
		int len = distance(counts.begin(), it);
		string str(len, 'a' + c_idx);
		for (int i = 1; i < len; i += 2) {
			str[i]++;
		}
		ans.append(str);

// printf("%d -> %d: len %d: \n", n, n - *it, len, str.c_str());

		n -= *it;
		c_idx = (c_idx + 2) % 26;
	}

	cout << ans << endl;
	return 0;
}