Problem:
Score : 300 points

Problem Statement

1000000000000001 dogs suddenly appeared under the roof of Roger's house, all of which he decided to keep. The dogs had been numbered 1 through 1000000000000001, but he gave them new names, as follows:

the dogs numbered 1,2,\cdots,26 were respectively given the names a, b, ..., z;

the dogs numbered 27,28,29,\cdots,701,702 were respectively given the names aa, ab, ac, ..., zy, zz;

the dogs numbered 703,704,705,\cdots,18277,18278 were respectively given the names aaa, aab, aac, ..., zzy, zzz;

the dogs numbered 18279,18280,18281,\cdots,475253,475254 were respectively given the names aaaa, aaab, aaac, ..., zzzy, zzzz;

the dogs numbered 475255,475256,\cdots were respectively given the names aaaaa, aaaab, ...;

and so on.

To sum it up, the dogs numbered 1, 2, \cdots were respectively given the following names:

a, b, ..., z, aa, ab, ..., az, ba, bb, ..., bz, ..., za, zb, ..., zz, aaa, aab, ..., aaz, aba, abb, ..., abz, ..., zzz, aaaa, ...

Now, Roger asks you:

"What is the name for the dog numbered N?"

Constraints

N is an integer.

1 \leq N \leq 1000000000000001

Input

Input is given from Standard Input in the following format:

N

Output

Print the answer to Roger's question as a string consisting of lowercase English letters.

Sample Input 1

2

Sample Output 1

b

Sample Input 2

27

Sample Output 2

aa

Sample Input 3

123456789

Sample Output 3

jjddja

Solution in Java (OpenJDK 11.0.6) (judge verdict: Wrong Answer)

import java.util.*;
 
public class Main {
 
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		long N = sc.nextLong();
		long num = 1;
		long index = 0;
		while (num < N) {
			num *= 26;
			index++;
		}
		List<Long> ts = new ArrayList<>();
		for (long i = index-1; -1 < i; i--) {
			ts.add((long) Math.pow(26, i));
		}
		long tmp = N;
		List<Long> ans = new ArrayList<>();
		for (Long l : ts) {
			if (26 < tmp) {
				ans.add(tmp/l);
			} else {
				ans.add(tmp);
			}
			tmp -= l*(tmp/l);
		}
		StringBuilder sb = new StringBuilder();
		boolean next = false;
		for (int i = 0; i < ans.size(); i++) {
			Long n = ans.get(ans.size()-1-i);
			if (next) {
				n--;
				next = false;
			}
			if (n < 1) {
				sb.append("z");
				next = true;
			} else {
				char c = (char)('a'-1+n);
				sb.append(c);
			}
		}
		System.out.println(N == 1 ? "a" :sb.reverse());
	}
}