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::stdin;

#[derive(Default)]
struct Scanner {
	buffer: Vec<String>
}

impl Scanner {
	fn next<T: std::str::FromStr> (&mut self) -> T {
		loop {
			if let Some(token) = self.buffer.pop() {
				return token.parse().ok().expect("Failed parse");
			}
			let mut input = String::new();
			stdin().read_line(&mut input).expect("Failed read");
			self.buffer = input.split_whitespace().rev().map(String::from).collect();
		}
	}
}

fn main() {
	let mut scan = Scanner::default();
	let mut x: u128 = scan.next();
	let mut ans: Vec<char> = vec![];
	while x > 0 {
		let mut c = ('a' as u8 + (x%26) as u8 - 1) as char;
		if c == '`' {
			c = 'z';
			x = x / 26 - 1;
		} else {
			x /= 26;
		}
		ans.push(c);
	}
	for i in (0..ans.len()).rev() {
		print!("{}", ans[i]);
	}
	println!("");
}