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: Wrong Answer)

#![allow(dead_code)]
#![allow(unused_imports)]
use ascii::{AsciiChar, AsciiStr, AsciiString};
use indexmap::IndexMap;
use itertools::*;
use libm::*;
use num::*;
use ordered_float::OrderedFloat;
use permutohedron::LexicalPermutation;
use proconio::marker::{Bytes, Chars};
use proconio::{fastout, input};
use std::cmp::{max, min, Ordering};
use std::collections::{BTreeMap, BTreeSet, BinaryHeap, HashMap, HashSet, VecDeque};
use std::mem::swap;

fn main() {
    input!(mut n: u128);

    let mut s = String::new();
    let mut i = 0;
    let mut cnt = 0;
    while cnt <= n {
        cnt += num::pow(26, i);
        i += 1;
    }
    i -= 1;
    if check_z(n) {
        for _ in 0..i {
            print!("z");
        }
        println!("");
        return;
    }
    for _ in 0..i {
        let p = num::pow(26, i - 1);
        let mut m = (n / p) as u8 % 26;
        if m == 0 {
            m = 25;
        } else {
            m -= 1;
        }
        s.push(('a' as u8 + m) as char);
        i -= 1;
        n %= p;
    }


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

fn check_z(n: u128) -> bool {
    if n % 26 != 0 {
        return false;
    }
    if n / 26 > 0 {
        return check_z(n / 26 - n / 26 % 26);
    }
    return true;
}