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 std::io;

fn main() -> io::Result::<()>{
    // read the input from console
    let n : u128 = {
	let stdin = io::stdin();
	let mut buf = String::new();
	stdin.read_line(&mut buf)?;
	buf.retain(|c| c!='\n');
	buf.parse().unwrap()
    };

    // head of convertion
    let res = convert(&n);
    println!("{}", res);
    Ok(())
}


fn convert(n : &u128) -> String {
    const NUM_OF_ALPHABET : u128 = 26;
    let mut n = *n;
    let mut res = Vec::new();                      

    while n > 0{
	n -= 1;
        let tmp = n % NUM_OF_ALPHABET;
        n /= NUM_OF_ALPHABET;   // updating n
	res.push((tmp) as u8 + 0x61);
    }
    res.reverse();
    String::from_utf8(res).unwrap()
}