#include <bits/stdc++.h>
#define rep(i, p, n) for (ll i = p; i < (ll)(n); i++)
#define rep2(i, p, n) for (ll i = p; i >= (ll)(n); i--)
using namespace std;
using ll = long long;
using ld = long double;
const double pi = 3.141592653589793;
const long long inf = 2 * 1e9;
const long long linf = 4 * 1e18;
const ll mod1 = 1000000007;
const ll mod2 = 998244353;
template <class T>
inline bool chmax(T &a, T b)
{    if (a < b)    {        a = b;        return 1;    }    return 0;}
template <class T>
inline bool chmin(T &a, T b)
{
    if (a > b)
    {
        a = b;
        return 1;
    }
    return 0;
}

//atcoder
#include <atcoder/all>
using namespace atcoder;
using mint1 = modint1000000007;
using mint2 = modint998244353;

vector<pair<ll, ll>> base={{-1, 0}, {1, 0}, {0, -1}, {0, 1}};


int main() {
    ll N;
    cin >> N;
    ll now=0;
    while(N>0) {
        ll temp=0;
        while(true) {
            if ((temp+2)*(temp+2)>N) {
                break;
            }
            temp++;
        }
        char P='a'+(now%13)*2, Q=P+1;
        cout << P;
        rep(i, 0, temp) {
            cout << Q << P;
        }
        N-=(temp+1)*(temp+1);
        now++;
    }
}