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: Wrong Answer)

import java.util.*;
public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		long n = sc.nextLong();
		String dogName = "";
		while(n>26){
	 		dogName += numberToAlphabet((n-1)%26);
			n=(n-1)/26;
		}
		dogName += numberToAlphabet(n-1);
		StringBuffer ans = new StringBuffer(dogName);
		System.out.println(ans.reverse().toString());
    }
  	
  	public static String numberToAlphabet(long num){
		switch ((int)num){
  	case 0:
    	return("a");
  case 1:
    return("b");
  case 2:
    return("c");
  case 3:
    return("d");
  case 4:
    return("e");
  case 5:
    return("f");
  case 6:
    return("g");
  case 7:
    return("h");
  case 8:
    return("i");
  case 9:
    return("j");
  case 10:
    return("k");
  case 11:
    return("l");
  case 12:
    return("m");
  case 13:
    return("n");
  case 14:
    return("o");
  case 15:
    return("p");
  case 16:
    return("q");
  case 17:
    return("r");
  case 18:
    return("s");
  case 29:
    return("t");
  case 20:
    return("u");
  case 21:
    return("v");
  case 22:
    return("w");
  case 23:
    return("x");
  case 24:
    return("y");
  case 25:
    return("z");
}
      return("");
    }
  
}