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 1.8.0) (judge verdict: Accepted)

import java.util.*;
import java.io.*;
public class Main {

	public static void main(String[] args) throws Exception{
		int num = 998244353;

		// TODO Auto-generated method stub
 		BufferedReader bf = new BufferedReader(new InputStreamReader(System.in));
 		PrintWriter out = new PrintWriter(System.out);
 		long n = Long.parseLong(bf.readLine());
 		long prod = 26;
 		int count = 1;
 		while(n-prod > 0){
 			n-=prod;
 			prod*=26;
 			count++;	
 		}
 		n-=1;
 		String a = Long.toString(n, 26);
 		int len = a.length();
 		StringJoiner sj1 = new StringJoiner("");
 		StringJoiner sj = new StringJoiner("");
 		for(int i = 0;i<count-a.length();i++){
 			sj.add("0");
 		}
 		sj1.add(sj.toString());
 		sj1.add(a);
 		
 		String c = sj1.toString();
 		StringJoiner ans = new StringJoiner("");
 		for(int i = 0;i<c.length();i++){
 			if (Character.isDigit(c.charAt(i))){
 				ans.add((char)(Integer.parseInt(c.charAt(i)+ "") + 97)+"");
 			}
 			else{
 				ans.add((char)((int)(c.charAt(i))+10)+"");
 			}
 		}
 		
 		out.println(ans.toString());
 		out.close();
 	}
}
 	
 
//StringJoiner sj = new StringJoiner(" "); 
//sj.add(strings)
//sj.toString() gives string of those stuff w spaces or whatever that sequence is