#include<iostream>
using namespace std;
int N;
main()
{
	cin>>N;
	string ans="";
	for(char c='a';N;c+=2)
	{
		int L=1;
		while(L*L<=N)L++;
		L--;
		N-=L*L;
		char d=c+1;
		ans+=c;
		for(;--L;)ans+=d,ans+=c;
	}
	cout<<ans<<endl;
}