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, fastout};
// use std::collections::VecDeque;


// fn rec_convert_digit_10_26(res_char_vec: &mut VecDeque<char>, n: f64) {
//     let current_digit = n.log(26.).floor();
//     if current_digit == 0. {
//         res_char_vec.push_front(((n + 96.) as u8) as char);
//     } else {
//         let current_digit_num = (n / (26. as f64).powi(current_digit as i32)).floor();
//         // println!("{} / {} = {}", n, (26. as f64).powi(current_digit as i32), current_digit_num);
//         // println!("{} -> {}", n, n - current_digit_num);
//         rec_convert_digit_10_26(res_char_vec, n - current_digit_num * (26. as f64).powi(current_digit as i32));
//         res_char_vec.push_front(((current_digit_num + 96.) as u8) as char);
//     }
//     
// }
// 
// // #[fastout]
// fn main() {
//     input! {
//         n: f64,
//     }
// 
//     let mut res_char_vec = VecDeque::new();
// 
//     rec_convert_digit_10_26(&mut res_char_vec, n);
// 
//     let res_string: String = res_char_vec.into_iter().collect();
// 
//     println!("{}", res_string);
// }

#[fastout]
fn main() {
    input! {
        mut n: usize,
    }
    let mut res = String::from("");
    let digit_char;
    if n % 26 == 0 {
        digit_char = 'z';
        n -= 26;
        n /= 26;
    } else {
        digit_char = ((n % 26) as u8 + 96) as char;
        n -= n % 26;
        n /= 26;
    }
    res.push(digit_char);
    while n > 0 {
        let digit_char;
        if n % 26 == 0 {
            digit_char = 'z';
            n -= 26;
            n /= 26;
        } else {
            digit_char = ((n % 26) as u8 + 96) as char;
            n -= n % 26;
            n /= 26;
        }
        res.push(digit_char);
    };

    println!("{}", res.chars().rev().collect::<String>());
}