#include<bits/stdc++.h>
#define rep(i,n,m) for(int i = (n); i <(m); i++)
#define rrep(i,n,m) for(int i = (n) - 1; i >=(m); i--)
using namespace std;
using ll = long long;
const int MAXS = 100000;

vector<ll> triangle;
vector<ll> triangle_plus;
void init()
{
    triangle.assign(MAXS, 0);
    triangle_plus.assign(MAXS, 0);
    rep(i, 0, MAXS) triangle[i] = (ll)i * (i+1) / 2;
    rep(i, 0, MAXS) triangle_plus[i] = triangle[i] + i;
}

int main()
{
    init();
    ll n;
    cin >> n;

    vector<int> nums;
    vector<ll>::iterator itr = upper_bound(triangle.begin(), triangle.end(), n);
    --itr;
    nums.push_back(itr - triangle.begin());
    n -= *itr;

    while (n > 1)
    {
        vector<ll>::iterator itr_plus = upper_bound(triangle_plus.begin(), triangle_plus.end(), n);
        --itr_plus;
        // cout << itr_plus - triangle_plus.begin() << ' '  << *itr_plus << endl;
        nums.push_back(itr_plus - triangle_plus.begin());
        n -= *itr_plus;
    }
    if (n == 1)
        nums.push_back(1);

    rep(i, 0, nums.size())
    {
        rep(j, 0, nums[i])
            printf("%c", 'a' + i % 26);
    }
    cout << endl;
    return 0;
}