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 proconio::input;

fn main() {
    input![
        mut n:i64
    ];

    let mut len = 1;
    let lowercase =  [
        '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 ans = loop {
        let mut sz = 1;
        for i in 0..len {
            sz*=26;
        }

        if n<=sz {
            n-=1;
            let mut ans = Vec::<char>::new();
            for _ in 0..len {
                ans.push(lowercase[(n%26) as usize]);
                n/=26;
            }
            ans.reverse();
            break ans
        }
        n-=sz;
        len+=1;
    };

    let ans:String = ans.into_iter().collect();
    println!("{}",ans);


}