#include <iostream>
#include <vector>
#include <cstdio>
#include <sstream>
#include <map>
#include <string>
#include <algorithm>
#include <queue>
#include <cmath>
#include <set>
using namespace std;

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

	long long lb = 0;
	long long ub = 100000;
	while(ub-lb > 1){
		long long mid = (lb+ub)/2;
		if( n > (mid)*(mid+1)/2){
			lb = mid;
		}else{
			ub = mid;
		}
	}

	long long aaaa = lb;
	string ans(aaaa, 'a');
	long long rem = n - ((aaaa)*(aaaa+1))/2;
	//cerr << aaaa << " " << (aaaa*(aaaa+1))/2 << endl;
	//cerr << rem << endl;

	for(int i=0; i<rem; i++){
		ans.push_back('c' + i%20);
	}

	cout << ans << endl;

	return 0;
}