#include <bits/stdc++.h>
using namespace std;

// b の数を x とすると、(x + 2) * (x + 3) / 2 - 2
// a -> 1
// aba -> 4
// ababa -> 8
// abababa -> 13

const long long MAX = 100000;

int main() {
    string res = "";
    char letter = 'a';
    
    long long N;
    cin >> N;
    while (N > 0) {
        long long low = -1, high = MAX;
        while (high - low > 1) {
            long long x = (low + high) / 2;
            if ((x + 2) * (x + 3) / 2 - 2 <= N) low = x;
            else high = x;
        }
        res += letter;
        for (int i = 0; i < low; ++i) {
            res += (char)(letter + 1);
            res += letter;
        }
        N -= (low + 2) * (low + 3) / 2 - 2;
        letter += 2;
    }
    cout << res << endl;
}