#include <bits/stdc++.h>
#define pi 3.14159265359
using namespace std;
 
string solve(int K, int z, bool down) {
	if(K == 0) return "";
	for(int i =1; i <= 100000; i++) {
		if(1LL*i*(i+1)/2 > 1LL*K) break;
		if(1LL*i*(i+1)/2+(down?-i/2:0) == 1LL*K) {
			string ret;
			for(int j =0; j < i; j++) ret +=('a'+z);
			return ret;}
		}
	for(int i =1; i <= 100000; i++) if(1LL*i*(i+1)/2+(down?(i-1)/2:i/2)-(down?i/2:0)+1 <= K && 1LL*(i+1)*(i+2)/2+(down?i/2:(i+1)/2)-(down?(i+1)/2:0)+1 > K) {
		string ret;
		for(int j =0; j < i; j++) ret +=('a'+z);
		ret +=('a'+z+1);
		ret +=solve(K-1LL*i*(i+1)/2-(down?(i-1)/2:i/2)+(down?i/2:0)-1,z+3,true);
		if(ret.length() > i+1) ret[i+1] =('a'+z+2);
		return ret;}
	}
 
int main() {
	int K;
	cin >> K;
	cout << solve(K,0,false) << "\n";
	return 0;}

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

MTAwMA==

1000