#include <iostream>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <string>
#include <iomanip>
#include <algorithm>
#include <cmath>
#include <stdio.h>
using namespace std;
#define int long long
int MOD = 1000000007;
string ts(int a) {
	string res;
	if (a < 26) {
		res.push_back('a' + (a % 26));
		return res;
	}
	else if (a == 26) {
		return "ab";
	}
	else if (a == 27) {
		return "ac";
	}
	else if (a == 28) {
		return "ad";
	}
	else if (a == 29) {
		return "ae";
	}
	else if (a == 30) {
		return "af";
	}
	else if (a == 31) {
		return "ag";
	}
	
	return res;
}
signed main() {
	cin.tie(0);
	ios::sync_with_stdio(false);
	int N;
	cin >> N;
	string res = "";
	res.resize(200, 'A');
	string t;
	int pos = 0;
	int a = 0;
	t = ts(a);
	if (N == 1) {
		cout << "a" << endl;
		return 0;
	}
	while (N > 1) {
		if (N % 2 == 0) {
			N /= 2;
			for (int i = 0; i < t.size(); i++) {
				res[pos + i] = t[i];
				res[200 - t.size() - pos + i] = t[i];
			}
			pos += t.size();
		}
		else {
			for (int i = 0; i < t.size(); i++) {
				res[pos + i] = t[i];
				res[200 - t.size() - pos + i] = t[i];
			}
			pos += t.size();
			a++;

			t = ts(a);
			N--;
		}
		
	}
	for (int i = 0; i < res.size();) {
		if (res[i] == 'A') {
			res.erase(res.begin() + i);
		}
		else {
			i++;
		}
	}
	cout << res << endl;
}