#include <bits/stdc++.h>

using namespace std;

int hoge(int x) {
	x *= 2;
	int ok = 1, ng = 50000;
	while (ng - ok > 1) {
		int mid = (ok + ng) / 2;
		if (mid * (mid + 1) <= x) ok = mid;
		else ng = mid;
	}
	return ok;
}

int main() {
	cin.tie(0);
	ios::sync_with_stdio(false);
	int n;
	cin >> n;
	string ans = "";
	for (int i = 0; n > 0 ; i++) {
		int cnt = hoge(n);
		ans += string(cnt, 'a' + i % 26);
		n -= cnt * (cnt + 1) / 2;
	}
	cout << ans << endl;
	return 0;
}