#include <bits/stdc++.h>
using namespace std;
using ll = long long;

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    ll n;
    cin >> n;
    auto f = [&](ll v){
        ll ok = 0, ng = 1 << 30, mid;
        while(ok + 1 < ng){
            mid = (ok + ng) / 2;
            if(mid * (mid + 1) <= 2 * v) ok = mid;
            else ng = mid;
        }
        return ok;
    };
    char c = 'a';
    string ans;
    while(n){
        ll v = f(n);
        n -= v * (v + 1) / 2;
        ans += string(v, c);
        c++;
    }
    cout << ans << '\n';
}