#include<iostream>
#include<algorithm>
#include<vector>
using namespace std;
string s;
int N;
main()
{
	cin>>N;
	if(N==1)
	{
	    cout<<"a"<<endl;
	    return 0;
	}
	vector<int>bit;
	while(N)
	{
		bit.push_back(N%2);
		N>>=1;
	}
	reverse(bit.begin(),bit.end());
	int cnt=0;
	for(int i=0;i<bit.size();cnt++)
	{
		int j=i+1;
		while(j<bit.size()&&bit[j]==0)j++;
		int t=j-i;
		i=j;
		if(i<bit.size())t++;
		if(cnt==0)t--;
		s+=string(t,cnt%26+'a');
	}
	string t=s;
	reverse(t.begin(),t.end());
	cout<<t+s<<endl;
}