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 Java (OpenJDK 11.0.6) (judge verdict: Accepted)

import java.util.Scanner;

public class Main{

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner scn=new Scanner(System.in);
		long n=scn.nextLong();
	        System.out.println( res(n));

	}
	public static StringBuilder res(long n){
		if(n<=0){
			StringBuilder sb=new StringBuilder();
			return sb;
		}
		if(n<=26){
			StringBuilder sb=new StringBuilder();
			char ch = (char)((n-1)+'a');
			sb.append(ch);
			return sb;
		}
		  StringBuilder ans=new StringBuilder();
		  if(n%26==0){
		StringBuilder a= res(n/26-1);
		  ans.append(a);
		  }else{
			  StringBuilder a= res(n/26);
			  ans.append(a);
		  }
		  
		    long val=n%26;
		    if(val==0){
		    	val=26;
		    }
		    char ch=(char)((val-1)+'a');
		    ans.append(ch);
		    return ans;
		
	}

}