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 Rust (1.42.0) (judge verdict: Accepted)

use proconio::input;
use std::str::from_utf8;
 
fn main() {
    input! {
        n: i64
    }

  	let mut a = n;
  	let mut index = 0;
  	let mut sum = 0;
	while 0 < n - sum {
        index += 1;
		sum += 26i64.pow(index);
  	}
  	let mut left = n + 26i64.pow(index) - sum - 1;
  	index -= 1; 
  	
  	let mut result = vec![];
  	while 0 < index {
        let temp = 26i64.pow(index);
        let char_code = ((left  / temp) + 97) as u8;
      	result.push(char_code);
        left = left % temp;

 		index -= 1;   
    }
  
    let char_code = (left + 97) as u8;
    result.push(char_code);
  	
	println!("{}", from_utf8(&result).unwrap());
}