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: Accepted)

using System;
using System.Linq;

namespace AtCoder
{
    public interface IInputReader
    {
        string Read();
    }

    public interface IOutputWriter
    {
        void Write(string output);
    }

    class ConsoleInputReader : IInputReader
    {
        public string Read() => Console.ReadLine();
    }

    class ConsoleOutputWriter : IOutputWriter
    {
        public void Write(string output) => Console.WriteLine(output);
    }

    class Program
    {
        static void Main(string[] args)
        {
            var reader = new ConsoleInputReader();
            var writer = new ConsoleOutputWriter();
            new Solver(reader, writer).Solve();
        }
    }

    public class Solver
    {
        private readonly IInputReader _inputReader;
        private readonly IOutputWriter _outputWriter;

        public Solver(IInputReader inputReader, IOutputWriter outputWriter)
        {
            _inputReader = inputReader;
            _outputWriter = outputWriter;
        }

        public void Solve()
        {
            var n = ReadLong();
            var alphabets = "abcdefghijklmnopqrstuvwxyz";
            var result = "";
            while (n > 0)
            {
                n -= 1;
                var a = (int) (n % 26);
                n /= 26;

                var c = alphabets[a];
                result = c + result;
            }

            _outputWriter.Write(result);
        }

        private string Read() => _inputReader.Read();
        private char[] ReadChars() => Array.ConvertAll(Read().Split(), a => a[0]);
        private int ReadInt() => int.Parse(Read());
        private long ReadLong() => long.Parse(Read());
        private double ReadDouble() => double.Parse(Read());
        private int[] ReadInts() => Array.ConvertAll(Read().Split(), int.Parse);
        private long[] ReadLongs() => Array.ConvertAll(Read().Split(), long.Parse);
        private double[] ReadDoubles() => Array.ConvertAll(Read().Split(), double.Parse);
    }
}