#include<iostream>
#include<iomanip>
#include<math.h>
#include<vector>
#include<algorithm>
#include<set>
#include<map>
#include<queue>
#include<stack>
#include<string>
#define INF 1000000000ll
#define MOD 1000000007ll
#define EPS 1e-10
#define REP(i,m) for(long long i=0; i<m; i++)
#define FOR(i,n,m) for(long long i=n; i<m; i++)
#define DUMP(a) for(long long dump=0; dump<(ll)a.size(); dump++) { cout<<a[dump]; if(dump!=(ll)a.size()-1) cout<<" "; else cout<<endl; }
#define ALL(v) v.begin(),v.end()
#define pb push_back
using namespace std;
typedef long long ll;
typedef pair<ll, ll> P;
typedef long double ld;

vector<string> vec;
ll pos=0;
void dfs(ll n, string& ret) {
	if(n==1||n==0) return;
	if(n%2) {
		n--;
		ret+=vec[pos];
		pos++;
		if(pos==26) pos=0;
		dfs(n,ret);
	} else {
		n/=2;
		ret+=vec[pos];
		dfs(n,ret);
	}
}


int main() {
	cin.tie(0);
	ios::sync_with_stdio(false);
	ll n;
	cin>>n;
	REP(i,26) {
		string str="";
		str+='a'+i;
		vec.pb(str);
	}
	string ret="";
	dfs(n,ret);
	ll m=(ll)ret.size()/2;
	REP(i,m) {
		ret+=ret.substr(m*2-2-i*2,2);
	}
	cout<<ret<<endl;
}