#include <bits/stdc++.h>

#define show(x) cerr << #x << " = " << x << endl

using namespace std;
using ll = long long;
using pii = pair<int, int>;
using vi = vector<int>;

template <typename T>
ostream& operator<<(ostream& os, const vector<T>& v)
{
    os << "sz=" << v.size() << "\n[";
    for (const auto& p : v) {
        os << p << ",";
    }
    os << "]\n";
    return os;
}

template <typename S, typename T>
ostream& operator<<(ostream& os, const pair<S, T>& p)
{
    os << "(" << p.first << "," << p.second
       << ")";
    return os;
}


constexpr ll MOD = 1e9 + 7;

template <typename T>
constexpr T INF = numeric_limits<T>::max() / 100;

int main()
{
    cin.tie(0);
    ios::sync_with_stdio(false);
    ll N;
    cin >> N;
    vector<int> ind;
    for (int i = 0; i < 64; i++) {
        if (N & (1LL << i)) {
            ind.push_back(i);
        }
    }
    for (int i = ind.size() - 1; i >= 1; i--) {
        ind[i] -= ind[i - 1];
        if (i != ind.size() - 1) {
            ind[i]++;
        }
    }
    if (ind.size() > 1) {
        ind[0]++;
    }
    show(ind);
    string st;
    for (int i = 0; i < ind.size(); i++) {
        const int cnt = ind[i];
        for (int j = 0; j < cnt; j++) {
            st.push_back('a' + (i % 26));
        }
    }
    cout << st << (char)('a' + (ind.size() % 26));
    reverse(st.begin(), st.end());
    cout << st << endl;

    return 0;
}