#include <cstdio>
#include <cstring>
#include <iostream>
#include <string>
#include <cmath>
#include <bitset>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <deque>
#include <algorithm>

using namespace std;
typedef long long int ll;

int main()
{
	int n;
	scanf("%d", &n);
	if(n==1){
		cout<<"doraemon"<<endl;
		return 0;
	}
	for(int i=0; i<n-1; i++){
		string str;
		str+='a';
		int i0=i;
		while(i0>0){
			str+=(char)('a'+(i0%26));
			i0/=26;
		}
		str+='a';
		cout<<str<<endl;
	}
	cout<<"an"<<endl;
	return 0;
}