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 Kotlin (1.3.71) (judge verdict: Accepted)

fun main() {
    val builder = StringBuilder()

    val n = readInputLine().toLong()

    var nTmp = n

    var len = 0

    var currentBase = 26L
    var currentSum = 0L

    while (true) {
        len++
        currentSum += currentBase

        if (currentSum >= n) {
            break
        }

        nTmp -= currentBase

        currentBase *= 26L
    }

    val ans = CharArray(len) { 'a' }

    val str = (nTmp - 1L).toString(26).padStart(len, '0')

    for (i in str.indices) {
        ans[i] = 'a' + str[i].toString().toInt(26)
    }

    builder.appendln(ans.joinToString(""))

    print(builder.toString())
}

fun readInputLine(): String {
    return readLine()!!
}