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 Go (1.14.1) (judge verdict: Wrong Answer)

package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
)

func newScanner() *bufio.Scanner {
	scanner := bufio.NewScanner(os.Stdin)
	scanner.Split(bufio.ScanWords)
	return scanner
}

var sc = newScanner()

func scanInt() int {
	sc.Scan()
	v, _ := strconv.Atoi(sc.Text())
	return v
}

func scanInts(n int) []int {
	a := make([]int, n)
	for i := 0; i < n; i++ {
		a[i] = scanInt()
	}
	return a
}

func scanString() string {
	if sc.Scan() {
		return sc.Text()
	}
	panic(sc.Err())
}

func main() {
	n := scanInt()
	answer := calcName(n)
	fmt.Println(answer)
}

func debug(a ...interface{}) {
	// fmt.Println(a...)
}

func calcName(n int) string {
	digit := 0
	base := 1
	for i, r := n, 0; i >= 1; i, r = i/26, i%26 {
		debug("i", i)
		if r != 0 {
			digit++
			base *= 26
		}
	}
	for i := 1; i < digit; i++ {
		prevBase := 1
		for j := 0; j < i; j++ {
			prevBase *= 26
		}
		debug("prevBase i", i, prevBase)
		base += prevBase
	}
	if base != 1 {
		base++
	}
	debug(digit, base)
	offset := n - base
	remainders := []int{}
	for i := offset; i >= 1; i /= 26 {
		remainders = append(remainders, i%26)
		debug(i)
	}
	name := ""
	for _, v := range remainders {
		name += string(v + 97)
	}
	return name
}