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)

#[allow(unused)]
use proconio::marker::*;
use proconio::{fastout, input};
#[allow(unused)]
use std::cmp::{max, min, Reverse};
#[allow(unused)]
use std::collections::{BinaryHeap, HashMap, HashSet, VecDeque};

#[fastout]
fn main() {
    input! {
        n: usize,
    }

    let mut i = 0;
    let mut ts = 26;
    let m = 25 * n + 1;
    while m >= ts {
        ts *= 26;
        i += 1;
    }
    // println! {"i: {}", i};

    let mut o = n;
    let mut ts = 26;
    for j in 0..i - 1 {
        o -= ts;
        ts *= 26;
    }
    o -= 1;
    // println!("o: {}", o);

    let mut ts = {
        let mut ts = 1;
        for j in 0..i - 1 {
            ts *= 26;
        }
        ts
    };
    // println!("{}", ts);

    let mut ans = vec![];
    for j in 0..i {
        let q = o / ts;
        let r = o % ts;
        ans.push(q);
        o = r;
        ts /= 26;
    }
    // println!("{:?}", ans);

    for &a in ans.iter() {
        let p = format!("{}", ('a' as u8 + a as u8) as char);
        print!("{}", p);
    }
    println!("");
}

fn r(n: usize) {}