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 ProblemC
{
    class Program
    {
        static void Main()
        {
            const int mod = 26;
            long N = GetLong();

            char[] name = new char[16];

            for(int i = 0; i < 16; i++)
            {
                if (N >= 1)
                {
                    long temp = N % mod;
                    if (temp == 0)
                    {
                        name[i] = 'z';
                    }
                    else
                    {
                        name[i] = (char)('a' + temp - 1);
                    }
                    N = (N - 1) / mod;
                }
                else
                {
                    break;
                }
            }

            for (int i = 16 - 1; i >= 0; i--)
            {
                if(name[i] != '\0')
                {
                    Console.Write(name[i]);
                }
            }
        }

        public static int GetInt() => int.Parse(Console.ReadLine());
        public static int[] GetIntArray() => Console.ReadLine().Split().Select(int.Parse).ToArray();
        public static double GetDouble() => double.Parse(Console.ReadLine());
        public static double[] GetDoubleArray() => Console.ReadLine().Split().Select(double.Parse).ToArray();
        public static long GetLong() => long.Parse(Console.ReadLine());
        public static long[] GetLongArray() => Console.ReadLine().Split().Select(long.Parse).ToArray();

    }
}