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 C# (.NET Core 3.1.201) (judge verdict: Runtime Error)

using System;
using System.Collections.Generic;
using System.Linq;

public class Program{
    public static void Main(){
        int number = int.Parse(Console.ReadLine());
        List<int> result = new List<int>();
        int baseNumber = 26;
        int alphabetStartNumber = 96;
        int time = 0;
        
        while (time != 1){
            time = 1;
            while (number >= Math.Pow(baseNumber, time)){
                time++;
            }
            
            if (time != 1){
                result.Add((int)(number / Math.Pow(baseNumber, time - 1)));
                number = (int)(number % Math.Pow(baseNumber, time - 1));
            } else{
                if (number % baseNumber != 0){
                    result.Add((int)(number % baseNumber));
                } else {
                    result[result.Count - 1]--;
                    result.Add(baseNumber);
                }
            }
        }
        
        foreach (int item in result.Where(a => a != 0)){
            Console.Write((char)(item + alphabetStartNumber));
        }
    }
}