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

int main(){
  int N,i,j;
  cin>>N;
  string s="";
  char c='a';
  while(N>0){
	int count=1;
	s+=c;
	while(N%2==0){
		N=N/2;
		s+=c;
		count*=2;
	}
	N=N-1;
	c+=1;
	if(c=='z') c='a';
  }
  string ans=s;
  for(i=0;i<s.size()-1;i++){
	ans+=s[s.size()-i-2];
  }
  cout<<ans<<endl;
  return 0;
}