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;
class Program
{
	static void Main()
	{
	    long a = long.Parse(Console.ReadLine());
      	string b = "";
      	long c = 0;
        long d = 0;
      	long e  = (long)Math.Floor(Math.Log(a, 26));
      	for(long i=1; i<=e; i++)
        {
          	d = (long)Math.Floor(Math.Pow(26, i));
          	c = (a / d % d == 0) ? 26 : (a / d % d);
            c += 96;
            b += ((Char)c).ToString();
            a -= d;
        }
      	if(a > 0)
        {
            c = a + 96;
            b += ((Char)c).ToString();
        }

        Console.WriteLine(b);
	}
}