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;
using System.Text;
using System.Threading.Tasks;

namespace abc171_c
{
    class Program
    {
        static void Main(string[] args)
        {
            var N = CIn.ReadInt();
            var list = new List<char>();        
            while(N > 0)
            {
                    list.Add((char)((N - 1) % 26 + 'a'));
                    N = (N - 1) / 26; 
            }  
            for(var i = list.Count - 1; i  >= 0; i--)
            {
                Console.Write(list[i]);
            }
        }
    }
    class CIn
    {
        private static readonly Queue<string> fieldBuffer = new Queue<string>();

        public static string Read()
        {
            if (fieldBuffer.Count == 0)
            {
                foreach (var field in Console.ReadLine().Split())
                {
                    fieldBuffer.Enqueue(field);
                }
            }

            return fieldBuffer.Dequeue();
        }

        public static int ReadInt() => int.Parse(Read());
        public static long ReadLong() => long.Parse(Read());
        public static double ReadDouble() => double.Parse(Read());

        public static string[] ReadStringArray(long n)
        {
            var array = new string[n];

            for (var i = 0; i < n; i++)
            {
                array[i] = Read();
            }

            return array;
        }

        public static int[] ReadIntArray(long n)
        {
            var array = new int[n];

            for (var i = 0; i < n; i++)
            {
                array[i] = ReadInt();
            }

            return array;
        }

        public static long[] ReadLongArray(long n)
        {
            var array = new long[n];

            for (var i = 0; i < n; i++)
            {
                array[i] = ReadLong();
            }

            return array;
        }
        public static double[] ReadDoubleArray(long n)
        {
            var array = new double[n];

            for (var i = 0; i < n; i++)
            {
                array[i] = ReadDouble();
            }

            return array;
        }
    }

}