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 ConsoleApp2
{
    class Program
    {
        static void Main(string[] args)
        {
            var N = GetLongNum();
            var str = "zabcdefghijklmnopqrstuvwxyz";
            var a = N / 26;
            var b = N % 26;
            var ans = string.Empty;

            while (true)
            {
                ans = str[(int)b].ToString() + ans;
                if (1 <= a && a <= 26)
                {
                    ans = str[(int)a].ToString() + ans;
                    break;
                }
                else if (a == 0)
                {
                    break;
                }

                b = a % 26;
                a = a / 26;
            }
            Console.WriteLine(ans);
        }

        private static long[] GetLongNumArray()
        {
            var input = Console.ReadLine().Split(' ');
            return input.Select(x => long.Parse(x)).ToArray();
        }

        private static long GetLongNum()
        {
            return long.Parse(Console.ReadLine());
        }

        private static string[] GetStringArray()
        {
            return Console.ReadLine().Split(' ');
        }

        private static string GetString()
        {
            return Console.ReadLine();
        }
    }
}