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)

namespace Test
{
    using System;
    using System.Collections.Generic;
    using System.ComponentModel;
    using System.Diagnostics;
    using System.Linq;
    using System.Reflection.PortableExecutable;
    using System.Runtime.CompilerServices;
    using System.Text;
    using System.Threading;
    using System.Xml.Serialization;

    public class Test
    {
        public static void Main(string[] args)
        {
            var t = new Test();
            var n = long.Parse(Console.ReadLine());
            var alfabetDic = new Dictionary<int, char>();
            var ansList = new List<int>();
            var sb = new StringBuilder();

            for (var i = 1; i <= 26; i++)
            {
                alfabetDic.Add(i, Convert.ToChar(96 + i));
            }
            t.calc(ansList, n);
            ansList.Reverse();
            foreach(var v in ansList)
            {
                sb.Append(alfabetDic[v]);
            }
            Console.WriteLine(sb.ToString()); 
        }


        public void calc(List<int> ansList, long n)
        {
            if (n <= 26)
            {
                ansList.Add((int)n);
                return;
            }
            
            ansList.Add((int)(n % 26));
            calc(ansList, n / 26);
        }
        public string[] ReadInput()
        {
            return Console.ReadLine().Split(' ');
        }

        public List<int> ParseIntList(string[] x)
        {
            var convertedList = new List<int>(x.Length);
            for (var i = 0; i < x.Length; i++)
            {
                convertedList.Add(int.Parse(x[i]));
            }

            return convertedList;
        }


        public List<double> ParseDoubleList(string[] x)
        {
            var convertedList = new List<double>(x.Length);
            for (var i = 0; i < x.Length; i++)
            {
                convertedList.Add(double.Parse(x[i]));
            }

            return convertedList;
        }

        public List<long> ParseLongList(string[] x)
        {
            var convertedList = new List<long>(x.Length);
            for (var i = 0; i < x.Length; i++)
            {
                convertedList.Add(long.Parse(x[i]));
            }

            return convertedList;
        }

        public int CountContainWords(string source, string word)
        {
            var count = 0;
            var loopCount = source.Length - (word.Length - 1);
            for (var i = 0; i < loopCount; i++)
            {
                if (source.Substring(i, word.Length) == word)
                {
                    count++;
                }
            }
            return count;
        }
    }
}