#include <iostream>
#include <cstdio>
#include <cassert>
#include <cstring>
#include <vector>
#include <valarray>
#include <array>
#include <queue>
#include <set>
#include <unordered_set>
#include <map>
#include <unordered_map>
#include <algorithm>
#include <cmath>
#include <complex>
#include <random>

using namespace std;
using ll = long long;
using ull = unsigned long long;
constexpr int TEN(int n) {return (n==0)?1:10*TEN(n-1);}

int main() {
    int N;
    cin >> N;
    string s;
    char base = 'a';
    while (N) {
        int i = 1;
        int sm = 1;
        while (true) {
            int nsm = 0;
            for (int j = 0; j <= i; j++) {
                nsm += j*2;
            }
            nsm += i+1;
            if (N < nsm) break;
            i++;
            sm = nsm;
        }
        for (int j = 0; j < i*2-1; j++) {
            if (j % 2 == 0) {
                s += base;
            } else {
                s += base+1;
            }
        }
        N -= sm;
        if (!N) break;
        N--;
        s += base+2;
        base += 3;
    }
    cout << s << endl;
//    for (int d: v) {
//        cout << d << endl;
//    }
    return 0;
}