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;

class Program
{
	static char[] alpha = new char[26];

	static void Main(string[] args)
	{
		int i;
		
		Int64 n = Int64.Parse(Console.ReadLine());
		

		for(i = 0; i < 26; i++)
        {
			alpha[i] = (char)('a' + (char)i);
        }

		string result = To26sin(n);

		Console.WriteLine(result);
		return;
	}

	//N進数に変換
	static string To26sin(Int64 val)
    {
		Int64 tmpVal;
		string ans = "";

        while (true)
        {
			val--;
			tmpVal = val % 26;
			ans = alpha[tmpVal] + ans;
			val = val/26;
			
			if(val <= 0)
            {
				break;
            }
        }

		return ans;
    }

}