#include <iostream>
#include <vector>
#define repeat(i,n) for (int i = 0; (i) < (n); ++(i))
typedef long long ll;
using namespace std;
ll sumto(ll i) { return i * (i+1) / 2; }
int main() {
    ll n; cin >> n;
    vector<int> ans;
    while (n > 0) {
        ll i = 1;
        while (sumto(i+1) <= n) ++ i;
        ans.push_back(i);
        n -= sumto(i);
    }
    repeat (i,ans.size()) {
        repeat (j,ans[i]) {
            cout << char((i%26) + 'a');
        }
    }
    cout << endl;
    return 0;
}