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 AtCoder.Abc
{
    class QuestionC
    {
        public static void Main(string[] args)
        {
            var sw = new System.IO.StreamWriter(Console.OpenStandardOutput()) { AutoFlush = false };
            Console.SetOut(sw);

            // 文字列の入力
            long s = long.Parse(Console.ReadLine());
            int cnt = 1;
            string result = "";
            double z = System.Math.Pow(26, 0);
            while (true)
            {
                z = z + System.Math.Pow(26, cnt);
                if (z > s)
                {
                    break;
                }
                cnt++;
            }
            for (int i = cnt; i > 0; i--)
            {
                z = System.Math.Pow(26, i-1);
                int cnt2 = 0;
                while (s >= z)
                {
                    s = s - (long)z;
                    cnt2++;
                }
                switch (cnt2)
                {
                    case 1:
                        result = result + "a";
                        break;
                    case 2:
                        result = result + "b";
                        break;
                    case 3:
                        result = result + "c";
                        break;
                    case 4:
                        result = result + "d";
                        break;
                    case 5:
                        result = result + "e";
                        break;
                    case 6:
                        result = result + "f";
                        break;
                    case 7:
                        result = result + "g";
                        break;
                    case 8:
                        result = result + "h";
                        break;
                    case 9:
                        result = result + "i";
                        break;
                    case 10:
                        result = result + "j";
                        break;
                    case 11:
                        result = result + "k";
                        break;
                    case 12:
                        result = result + "l";
                        break;
                    case 13:
                        result = result + "m";
                        break;
                    case 14:
                        result = result + "n";
                        break;
                    case 15:
                        result = result + "o";
                        break;
                    case 16:
                        result = result + "p";
                        break;
                    case 17:
                        result = result + "q";
                        break;
                    case 18:
                        result = result + "r";
                        break;
                    case 19:
                        result = result + "s";
                        break;
                    case 20:
                        result = result + "t";
                        break;
                    case 21:
                        result = result + "u";
                        break;
                    case 22:
                        result = result + "v";
                        break;
                    case 23:
                        result = result + "w";
                        break;
                    case 24:
                        result = result + "x";
                        break;
                    case 25:
                        result = result + "y";
                        break;
                    case 26:
                        result = result + "z";
                        break;
                    default:
                        break;
                }
            }
            
            Console.WriteLine(result);

            Console.Out.Flush();
        }
    }
}