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 Java (OpenJDK 11.0.6) (judge verdict: Wrong Answer)

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        double N = scanner.nextDouble();
        int k;
        double r = 0, l = -1;
        for (k = 1; ; k++) {
            l = l + Math.pow(26,k - 1);
            r = r + Math.pow(26,k);
            if (N <= r && N >= l) {
                break;
            }
        }
        String ans = "";
        N -= l;
        for (int i = k; i >= 1; i--) {

            double num = N / Math.pow(25.99999, i - 1);
            if (N == 0) {
                num = 25.5;
            }
            int unum, lnum;
            lnum = (int) Math.floor(num);
            unum = (int) Math.ceil(num);
            unum = unum > 26 ? 26 : unum;
            ans += fun(unum);
            N -= (double) lnum * Math.pow(26, i - 1);
        }
        System.out.println(ans);
    }


    public static char fun(int p) {
        char c = (char) (96 + p);
        return c;
    }
}