#include <iostream>
#include <vector>
#include <string>
#include <cmath>
#include <algorithm>
#include <utility>
#include <queue>
#include <set>
#include <map>

using namespace std;
typedef  long long ll;
typedef pair<int,int> PII;
typedef vector<int> VI;
typedef vector<VI> VVI;
#define  MP make_pair
#define  PB push_back
#define inf  1000000007

int main(){
	ll n;
	cin >> n;
	if(n==1){
		cout << "a" << endl;
		return 0;
	}
	vector<int>v;
	while(n!=0){
		ll x = 1;
		for(int i=0;i<100;i++){
			if(x>n){
				v.push_back(i-1);
				n -= x/2;
				break;
			}else{
				x*=2;
			}
		}
	}
	string s;
	if(v.size()==1){
		for(int i=0;i<v[0];i++){
			s.push_back('a');
		}
		s += s;
		cout << s << endl;
	}else{
		v.push_back(0);
		reverse(v.begin(),v.end());
		for(int i=1;i<v.size();i++){
			if(i!=((int)v.size()-1)){
				for(int j=0;j<v[i]-v[i-1]+1;j++){
					if('a'+i-1>'z'){
						s.push_back('a'+('a'+i-1-'z'));
					}else{
						s.push_back('a'+i-1);
					}
				}
			}else{
				for(int j=0;j<v[i]-v[i-1];j++){
					if('a'+i-1>'z'){
						s.push_back('a'+('a'+i-1-'z'));
					}else{
						s.push_back('a'+i-1);
					}
				}
			}
		}
		string tmp = s;
		reverse(tmp.begin(),tmp.end());
		s += tmp;
		cout << s << endl;
	}
	return 0;
}