#include <iostream>
#include <vector>
#include<algorithm>
#include<iomanip>
#include<queue>
#include<deque>
#include<map>
#include<set>
#include<bitset>
#include<math.h>
using namespace std;
#define rep(i,n) for(int i=0;i<(int)(n);i++)
#define REP(i,m,n) for(int i=m;i<(int)(n);i++)
typedef long long ll;
typedef pair<int,int> pint;
const ll mod= 998244353;
const int inf=1e9+7;
const ll  longinf = 1LL<<60;
int dx[4]={1,0,-1,0}, dy[4]={0,1,0,-1};


int main(){ 
  int n;
  cin>>n;
  if(n==1){
    cout<<"yukicoder"<<endl;
    return 0;
    }
  string s="",t="";
  char x='a';
  while(n>1){
    s+=x;
    if(n%2){
      if(x!='z')x++;
      else x='a';
      s+=x;
      }
    n/=2;
    }
  cout<<s<<"z";
  reverse(s.begin(),s.end());
  cout<<s<<endl;
  
  return 0;
  }