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);
		// スペース区切りの整数の入力
        String alf="abcdefghijklmnopqrstuvwxyz";
        long N=sc.nextLong();
        long defN=N;
        StringBuilder s = new StringBuilder("");
        int zerof=0;
        for(int i=13;i>=0;i--){
          int m=(int)(((N-(N%pow(i,26)))/pow(i,26)));
          if(zerof==1||m!=0){
          zerof=1;
            if(m-1>0){
          s.append(String.valueOf(alf.charAt(m-1)));
            }else{
              s.append("a");
            }
          }
          N=N%pow(i,26);
        }
      if(defN!=0){
        System.out.println(s.toString());
      }else{
        System.out.println("a");
      }
}
  public static long pow(int k,long n){
    long t=1;
    for(int i=0;i<k;i++){
      t=t*n;
    }
    return t;
  }
}