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(
    non_snake_case,
    unused_variables,
    unused_assignments,
    unused_mut,
    dead_code
)]
use proconio::input;
// use proconio::marker::Usize1;
//use proconio::marker::Chars;
//use std::collections::HashSet;
//use std::cmp::*;
fn main() {
    input! {
       mut n:u64
    }
    // 26^4+26^3+(26^2+26)
    // 2^50以下の数。
    // 1_000_000_000_000_001 < 26^11
    //for i in 651..760 {
    //    n = i as u64;
    let mut ans: String = String::new();
    let mut p: Vec<u64> = vec![1u64; 11];
    let mut q: Vec<u64> = vec![1u64; 11];
    p[0] = 1;
    q[0] = 0;
    for i in 1..11 {
        p[i] = 26u64.pow(i as u32);
        q[i] = p[i] + q[i - 1];
    }
    for i in (0..11).rev() {
        if i == 0 && n <= 26 {
            if n == 0 {
                n += 26;
            }
            ans.push((n as u8 - 1 + 'a' as u8) as char);
            continue;
        }
        if n <= q[i] {
            continue;
        }
        let baisu = n - q[i];
        let mut shou = ((baisu + p[i] - 1) / p[i]) as u8;
        //println!("{},{},{}", baisu, p[i], shou);
        if shou == 26 {
            ans.push('z');
        } else {
            ans.push((shou - 1 + 'a' as u8) as char);
        }
        n = n % p[i];
    }
    println!("{}", ans);
    //}
}