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)

use proconio::input;
fn main() {
    input!{
        n: u64,
    };
    let mut t = n;
    let al = vec!["", "a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z"];
    let mut cs : Vec<i32> =  Vec::new(); //chars
    while t != 0 {
        let idx = t % 26;
        t = t / 26;
        cs.push(idx as i32);
    }
    cs.reverse();
    for i in 0..cs.len() {
        if cs[i] == 0 && i > 0 {
            // eprintln!("{}: decrement", i);
            cs[i-1] = cs[i-1] - 1;
            if cs[i-1] == -1 {
                cs[i-1] = 26;
            }
        }
        if cs[i] == 0 {
            cs[i] = 26;
        }
        // eprintln!("{}:{}:{}",i ,cs[i], al[cs[i] as usize]);
        // if c == 0 {
        //     cs[i-1] = cs[i-1]-1;
        // }
    }
    for i in 0..cs.len() {
        print!("{}", al[cs[i] as usize]);
    }
    println!("");
}