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: Wrong Answer)

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace _171C
{
    class Program
    {
        static void Main(string[] args)
        {
            long N = long.Parse(Console.ReadLine() ?? string.Empty);
            long NameLength = CalculateNameLength(N);
            //Console.WriteLine("名前文字数："+NameLength.ToString());
            char[] Name = new char[NameLength];
            long Sho = N;

            const char AsciiOffset = (char) 96;

            for (int i = 0; i < NameLength; i++)
            {
                long amari = 0;
                if (Sho < 27)
                {
                    amari = Sho;
                    //Console.WriteLine("あまり" + (int)amari);
                }
                else
                {
                    amari = (char)(Sho % 26);
                    //Console.WriteLine("あまり" + (int)amari);
                    Sho = (long)(Sho / 26);
                    //Console.WriteLine("商" + Sho.ToString());
                }
                Name[NameLength - i -1] = (char) (amari + AsciiOffset);
            }
            Console.WriteLine(Name);
        }

        private static long CalculateNameLength(long l)
        {
            long sum = 0;
            long i = 0;
            while (l > sum)
            {
                i++;
                sum += (long) Math.Pow(26, i);
            }

            return i;
        }
    }
}